latest advances in survey design and statistical meth- ods, presents findings in a variety of formats, and pro- vides data that address educational issues of current interest. Through the collection of data and the pre- sentation of results in a variety of publications, including annual reports, information on the status of the educational system in the United States is avail- able for use by researchers, professional educational organizations, legislators, and the general public. Data Collection The NCES collects data primarily through the adminis- tration of surveys covering a variety of topics, including educational assessments, early childhood experiences, elementary and secondary education, international edu- cational issues and trends, and postsecondary education. Educational Assessments The NCES collects and reports information on the academic performance of students in the nation’s schools and the literacy skills of the nation’s adults. The National Assessment of Educational Progress (NAEP), also known as the ‘‘Nation’s Report Card,’’ is the only nationally representative and continuing assessment of the academic achievement of students in various subjects. Through the National Assess- ments of Adult Literacy (NAAL), basic literacy and mathematical skills of adults are assessed, and with this information, the status of adult literacy, national trends in adult literacy, and relationships between lit- eracy and adult characteristics are revealed. Early Childhood The NCES collects data on children’s health and early care school experiences through two longitudi- nal studies: the Early Childhood Longitudinal Study, Kindergarten Class of 1998–99 (ECLS-K) and the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B). These studies are two of the first nation- ally representative studies of children’s developmental and educational experiences from birth to early adolescence. Elementary/Secondary The NCES collects data on the condition of public and private education through the Common Core of Data (CCD), a database that holds information on the nation’s public elementary and secondary schools (approximately 94,000) and school districts (approxi- mately 17,000); the Schools and Staffing Survey (SASS), which collects information on principals, tea- chers, schools, school districts, and library media cen- ters; the Private School Survey (PSS), which compiles a list of the nation’s private schools; and the National Household Education Surv ey (NHES), which is used to collect information on a variety of educational issues— for example, in 2003, surveys focusing on Adult Educa- tion for Work Related Reasons and Parent and Family Involvement in Education were administered. International The International Activities Program provides data comparing the educational experiences of students and educational trends in the United States to those in other countries. Trends in mathematics and science achievement, literacy achievement, and civics are among the issues examined by these surveys. Postsecondary Through the administration of the Integrated Post- secondary Education Data System (IPEDS) Survey, a variety of data on the nation’s 9,800 public and pri- vate postsecondary institutio ns, including enrollments, program completions, faculty, staff, finances, and academic libraries, are collected. Additional surveys collect data on students, fi nancial aid, postsecondary faculty, degree recipients, and transcripts. Annual Reports In addition to the statistical information collected, the NCES presents findings in a variety of formats, including five main annual reports: The Condition of Education, The Digest of Education Statistics, Indica- tors of School Crime and Safety, Projections of Edu- cation Statistics ,and Education Statistics Quarterly. First, The Condition of Education summarizes development and trends in education using the most recent available data. Thi s report includes findings from six main areas: (1) enrollment trends and student characteristics at all levels; (2) student achievement and the long-term effects of education; (3) student effort and rates of progress through the educational sys- tem; (4) the contexts of elementary and secondary National Center for Education Statistics 721 education; (5) the contexts of postsecondary education; and (6) support from society for learning, including parental and community support, and public and pri- vate financial support of all levels of education. Second, The Digest of Education Statistics com- piles statistical information on topics of current inter- est covering a wide range of educational issues at all levels. Issues discussed include the number of schools, colleges, teachers, enrollments, and graduates as well as educational attainment, federal funds for education, libraries, employment and income of grad- uates, and international educational comparisons. Third, Indicators of School Crime and Safety is pub- lished jointly by the NCES and the Bureau of Justice Statistics. It examines crime occurring on the way to and from school, as well as in school. Through the National Crime Victimization Survey, the School Crime Supplement to the National Crime Victimization Sur- vey, the Youth Risk Behavior Survey, the School Survey on Crime and Safety, and the Schools and Staffing Survey, data on the nature of crime in schools are collected and presented from the perspectives of stu- dents, teachers, principals, and the general population. Fourth, Projections of Education Statistics provides projections on major educatio n statistics, such as statis- tics on elementary and secondary schools’ enrollment, graduates, teachers , and expenditures, as well as enroll- ment, degrees earned, and expenditures of institutions of higher education. Data from the past 15 years, as well as projections for the fut ure, are displayed in text, tables, and figures in the publication. Finally, Education Statistics Quarterly is a compre- hensive overview of all NCES projects. Each issue includes short publications and summaries of all NCES publications and data pro ducts recently released. Furthermore, training and funding opportunities are included, as well as a featured topic with commentary. Carolyn L. Carlson See also Descriptive Statistics; Longitudinal Research; National Assessment of Educational Progress Further Readings Forgione, P. D. (1999). Using federal statistics to inform educational policy and practice: The role of the National Center for Education Statistics (presented to the U.S. Senate Committee on Health, Education, Labor, and Pensions). Washington, DC: Office of Educational Research and Improvement. Snyder, T. D., Tan, A. G., & Hoffman, C. M. (2006). Digest of Education Statistics , 2005 (NCES 2006–030). Washington, DC: U.S. Government Printing Office. U.S. Department of Education, National Center for Education Statistics. (2006). The Condition of Education 2006 (NCES 2006–071). Washington, DC: U.S. Government Printing Office. Web Sites National Center for Education Statistics: http://www.nces.ed.gov N ATURALISTIC O BSERVATION Naturalistic observation refers to the scientific study of the social interactions of children and adults within their native environments, such as in school or at home, or within artificial situations designed to elicit specific behaviors of interest that occur in native environments, such as child social and problem- solving skills with peers or parents. In educational psychology, the phrase is most commonly used to describe studies in which researchers or practitioners attempt to observe subjects of interest as unobtru- sively and impartially as possible. Observation techni- ques were developed throughout the 20th century but came into prominence with the rise of behavior ther- apy and behavioral assessment in the 1960s. Natural- istic observation is particularly useful for describing the social, physical, and temporal contexts within which educational activities occur. Observation data can be used to address a wide variety of basic and applied research questions in relevant areas such as learning, instruction, assessment, evaluation, diagno- sis, and intervention. An early proponent of naturalistic observation was Arnold Gesell, a student of f ounding American psycho- logist G. Stanley Hall, who developed coding systems to record the behavior of infants during the 1920s. Gesell employed a variety of techniques that would become commonplace in observational studies, including the use of one-way screens to minimize observer influence and motion picture cameras to capture observations for later study. Florence Goodenough developed a short-sample technique, whereby children were observed for brief per- iods of time and the presence or absence of specific behaviors were noted. Over the next decade, a variety of other psychologists ob served children in nursery 722 Naturalistic Observation schools and other commonplace settings and used cod- ing systems to record social interactions. Henry Murray employed observational techniques with adults during the late 1930s, which he then applied to personnel selection for the U.S. Office of Strategic Services during World War II. His work included the early use of role-playing as a way to sample behavior during normally occurring social situations. During this same time period, Kurt Lewin favored observation techniques over psychological tests and played a key role in popularizing the use of observational techniques. Roger Barker worked with Lewin in studies of frustration in children, and with colleagues later coded the moment-to-moment beha- viors of a child documented in One Boy’s Day. Another seminal figure in naturalistic observation was Robert Bales, who developed a method for categoriz- ing behaviors documented in the influential book Interaction Process Analysis. The rise of behavior therapy during the 1950s and early 1960s brought observational techniques into widespread use in psychology. Operant behavioral procedures pioneered by psychologist B. F. Skinner and colleagues had particular influence in educational psychology. In early studies, observational measures of child behaviors were employed to monitor the effectiveness of various techniques to change beha- viors within the school context. Two key research groups that were among the first to employ behavioral observational techniques extensively were those of Sidney Bijou and Gerald R. Patterson. During the late 1960s, Patterson, John B. Reid, and colleagues spear- headed the development of sophisticated behavioral observation coding systems to study child aggression and other antisocial behaviors within family and classroom settings. Since this period, a wide variety of coding systems have been developed by educa- tional, clinical, and developmental psychologists to monitor various aspects of social interactions within school, home, clinic, and laboratory settings. The hallmark of naturalistic observation is the accu- rate recording of specific behaviors at the time they occur within a real-life setti ng or situation of interest. To accomplish this, either a n observer must be present so that coding can be done ‘‘live,’’ or an audio or visual recording device must be active so that coding can be done at a later date. To ensure impartiality, observers should not personally know the research sub- jects or the details of their i nvolvement in the research study, and to ensure accuracy, observers should be adequately trained and moni tored in the reliable use of a well-developed and tested descriptive coding system. Clearly, two important aspects of naturalistic observation are the characteristics of the coding sys- tem to be employed and the ability of observers to appropriately apply the coding system. There are two major types of coding systems, those that focus on the discrete behaviors by a given individual, or ‘‘micro’’ coding systems, and those that focus on larger series of a variety of presumably related behaviors by one or more individuals, or ‘‘macro’’ coding systems. Within each type, coding systems have been devel- oped to code a variety of details of social interactions, including physical movement, language content, affective tone, physical location or position relative to others, and the time spent in any of the above. Regardless of the type or purpose, a coding system must clearly specify what is to be recorded; should contain a limited number of mutually exclusive code categories; and should not require observers to make inferences about phenomena that cannot be seen, such as the internal thoughts or feelings of an individual about a given behavior. Basic training in the reliable use of a comprehensive coding system usually takes several months of intensive work by a coding team. Training in relatively simple coding systems may take less time, but it requires a significant amount of time investment by a team nonetheless. Once data are being collected for a study, the day-to-day reliability of the observers in continuing to apply the coding system accurately should be monitored. Generally, this is done through the use of regular, random checks where two observers code the same interaction, and their agreement on specific codes is checked. Usually, from 10 % to 20 % of observations are coded by two or more observers to conduct such reliability checks. Observers who do not meet set reliability standards should be removed from the data collection process and provided further training. Because of the recognition that human behavior tends to vary across situations, researchers who col- lect naturalistic observation data often attempt to col- lect multiple measures of the behaviors that are being observed. This includes multiple observations within the same setting, observations across different set- tings, and observations as well as impressions by sev- eral raters. For example, child physical aggression might be assessed via micro-observational coding of several home, classroom, and playground interactions, Naturalistic Observation 723 as well as by more global questionnaires completed by parents, teachers, children, and peers. Important questions within most areas where naturalistic obser- vation is used include how many observations and what length of time is required to obtain a truly repre- sentative sample of the behavior of an individual, how study participant characteristics such as culture affect the reliability and validity of coding systems, and how the significant costs related to creating and maintaining a reliable coding team can be managed to enable the widespread use of observational techniques in research and practice settings. J. Mark Eddy See also Applied Behavior Analysis; Evaluation; Qualitative Research Methods Further Readings Bales, R. F. (1951). Interaction process analysis. Cambridge, MA: Addison-Wesley. Barker, R. G., & Wright, H. F. (1951). One boy’s day. New York: Harper & Row. Jones, R. R., Reid, J. B., & Patterson, G. R. (1975). Naturalistic observations in clinical assessment. In P. McReynolds (Ed.), Advances in psychological assessment (Vol. 3, pp. 42–95). San Francisco: Jossey-Bass. Mash, E. J., & Terdal, L. G. (Eds.). (2001). Behavioral assessment of childhood disorders (3rd ed.). New York: Guilford. McReynolds, P. (1986). History of assessment in clinical and educational settings. In R. O. Nelson & S. C. Hayes (Eds.), Conceptual foundations of behavioral assessment (pp. 42–80). New York: Guilford. Webb, E. J., Campbell, D. T., Schwartz, R. D., & Sechrest, L. (2004). Unobtrusive measures (Rev. ed.). Thousand Oaks, CA: Sage. N EUROSCIENCE Neuroscience is the study of nervous system function. It is a discipline that draws on a number of other fields, including anatomy, biology, chemistry, genetics, phar- macology, and psychology. The phenomena studied by neuroscientists range from processes within a cell, including production and trafficking of proteins within cells, to understanding brain systems that underlie con- sciousness, with studies of changes in cell shape and function, brain chemicals, and hormones as just a few examples of some of the intermediate areas of study. With regard to education, the brain is the critical sub- strate that mediates new learning. The brain must be sufficiently flexible to allow new information to be encoded while minimizing previous information that is forgotten. Neuroscience is a critical approach to under- standing which situations are likely to maximize new learning. Not surprisingly, with such a complicated subject to study—the nervous system—a number of subdisciplines have devel oped that offer different approaches within this research area. Important contri- butions of neuroscience to the study of brain diseases are mentioned in this entry. S ome general neuroscience terminology and techniques a re described, followed by a section that addresses how neuroscience may be bene- ficial for improving education. Cross-Disciplinary Approaches for Studying Brain Diseases Several diverse approaches for studying the brain have been developed that emphasize different levels of analysis. Molecular and cellular neuroscience emphasizes how the machinery within a cell operates. The results of these research areas have given an appreciation of the complexity of cell structure and function. However, cells within the brain do not act in isolation but rather communicate with each other. Systems neuroscience emphasizes how groups of brain cells interact with other groups of brain cells. This area can yield insights about how one group of brain cells can cooperate (or not) to affect activity in other groups of brain cells. This area has benefited from approaches using computational neuroscience, in which mathematics is used to try to describe how a group of neurons could function to mediate some aspect of processing. Computational neuroscience can yield plausible hypotheses that can then be tested with laboratory-based methodologies. Neuroanatomical approaches are used to identify specific brain regions and to describe the nature of con- nections between different brain regions. Understand- ing how the brain is ‘‘wired’’ is important for testing hypotheses about which brain regions influence each other. Neuropharmacological approaches emphasize studying how drugs affect the brain. Behavioral neuros- cientists study the brain mechanisms underlying a range of behaviors, including remembering, feeding, or defensive behaviors. These general research areas are indicative of the diversity of approaches for studying 724 Neuroscience the brain, but are not by any means exhaustive. Despite increased understanding of brain function using each of these approaches, it has become clear that, to fully understand phenomena related to the brain, multiple levels of analysis need to be implemented. For exam- ple, if somebody is interested in the effects of a particu- lar drug, one may study the effects of that drug on the brain itself. Does the drug change the activity of proteins within the cell? Does the drug alter interac- tions between cells? If so, which cells? Researchers also want to know about the effects of the drug on cognitive processes such as attention and memory as well as changes in behavior. The ultimate goal is to be able to assess exactly which changes in the brain con- tribute to changes in cognition and behavior. Thus, although there are a number of subdisciplines that emphasize different aspects o f brain functioning, a com- plete understanding of complex phenomena requires cross-fertilization between different approaches within neuroscience. Neuroscientists are de dicated not only to under- standing how the brain works under ‘‘normal’’ condi- tions, but also to assessi ng how the brain becomes dysfunctional in some disease s. Several typical strate- giesareemployedintryingtostudybraindiseases. Of course, it is important to collect information about the patients with the disease to characterize the symp- toms and begin to assess the underlying causes. For a particular disease, it is important to characterize the psychological deficits as we ll as the brain regions, neu- rotransmitter systems, and molecular markers affected by the disease. Clearly, multiple levels of analysis are required to characteriz e the disease process. For many diseases, animal models can be devel- oped, at least for some aspects of the disease, and then changes in the brain’s neurochemistry and molecular and cellular functioning can be assessed. Animal models also offer an opportunity to test pre- liminary treatments for some brain diseases. An important consideration in animal models is the extent to which findings translate to the human condition. Neuroscientists have an excellent history of success- fully translating research from animal models to the human condition. For example, early animal research using the drug reserpine, which depletes certain che- micals in the brain, was observed to produce symp- toms similar to those in depression. Many drugs now, including a class of drugs known as serotonin-specific reuptake inhibitors, such as Prozac, were developed based on the early findings with animals. Another example involves the treatment of Parkinson’s dis- ease. Animals administered a particular drug, MPTP, exhibit symptoms and brain pathology similar to patients with Parkinson’s disease. Based on studying the brain changes in these animal models, damage to particular brain structures (and later deep brain stimu- lation of these structures, which is reversible) was shown to alleviate some symptoms in Parkinson’s dis- ease. These examples demonstrate how basic neuro- science research can contribute to treatments for devastating neuropsychiatric diseases. Future success in treating brain-based diseases likely depends on integration of research from multiple levels of analy- sis, from molecular/cellular to behavior. General Terminology in Neuroscience This section initially describes concepts at the level of brain cells and then moves to a discussion of brain regions. The cells responsible for much of the com- munication within the brain are neurons. Signaling between neurons is accomplished through both elec- trical and chemical means. One of the major compo- nents of neurons is the cell body, which is where the nucleus containing genetic information is located along with a number of proteins necessary for main- taining the neuron’s health. A thin protrusion from the cell body, the axon, carries electrical signals to the axon terminal. The axon terminal contains chemi- cals used in neuronal communication, known as neu- rotransmitters. When an electrical signal (an ‘‘action potential’’) is conducted along an axon and reaches the axon terminal, the terminal will release neuro- transmitters into an area known as the synaptic cleft or synapse. The neuron-releasing neurotransmitter can be identified as the presynaptic neuron. The neuro- transmitter binds to receptors on a nearby neuron (the postsynaptic neuron) and has effects on that postsyn- aptic neuron. These effects include increasing or decreasing the likelihood that the postsynaptic neuron will fire an action potential or altering the rate at which proteins are synthesized. The actions of the neurotransmitter can be terminated in several ways, including by enzymes or by being taken back up into the presynaptic neuron. Many different neurotransmitters have been identi- fied, and one significant goal of neuroscience is to understand what these neurotransmitters uniquely contribute to neuronal processing as well as how these Neuroscience 725 neurotransmitters become altered in some neuropsy- chiatric diseases. Some of the most prevalent neuro- transmitters in the brain are amino acids, including glutamate and gamma-aminobutyric acid (GABA). Among other functions, glutamate is thought to be an important neurotransmitter for learning and memory. GABA is implicated in anxi ety. Drugs such as Valium, which are used to treat anxiety, act at the same receptor complex as GABA. Other important neurotransmitters include a group of neurotransmitters known as catecholamines, which include norepinephrine and dopamine. Norepineph- rine is involved in the arousal of an organism. Increases in dopamine in some brain regions are a con- sistent feature of most drugs of abuse. Furthermore, increased activity of the dopamine system is associ- ated with symptoms in schizophrenia. Damage to a particular dopaminergic pathway appears to underlie some of the motoric deficits in Parkinson’s disease. Another neurotransmitter, serotonin, has been impli- cated in impulsivity and depression. Some drugs used to treat depression, such as Prozac, allow serotonin to act on receptors for a longer period of time. Another important neurotransmitter is acetylcholine. Loss of neurons that release acetylcholine has been associated with the cognitive deficits in Alzheimer’s disease. Many of the drug treatments for Alzheimer’s disease act by blocking the breakdown of acetylcholine. The transmitters mentioned abov e are typically considered ‘‘classical’’ neurotransmitters and have been studied extensively. However, numerous other molecules, even some gases, appear to have properties similar to classi- cal neurotransmitters and will be important for neuros- cientists to continue to study in the future. The actions of neurotra nsmitters are mediated through receptors. Receptors are simply proteins that commonly span the outside and inside of the cell, with most neurotransmitters binding to a portion of recep- tors outside of the cell. For each of the classical neuro- transmitters, there are a number of receptors. Some goals of neuropharmacology include identifying the different types of receptors for a particular neurotrans- mitter as well as where these receptors are located within the brain. This research is important because some neurotransmitters appe ar to have different actions mediated through different receptor subtypes. In some cases, it is desirable to develop a drug that acts at only a particular receptor subtype in order to limit the drug’s side effects. For example, drugs used to treat depres- sion by increasing serotonin levels appear to provide most of the antidepressant effects by acting at the sero- tonin-1 receptor. However, increasing serotonin levels also causes more serotonin to bind to other serotonin receptors, including serotonin-2 and serotonin-3 recep- tors. Increased serotonin binding at serotonin-2 and serotonin-3 receptors appears to contribute to some side effects of this class of antidepressants, including sexual dysfunction and nausea. Thus, a goal of researchers is to develop drugs that target the receptor that provides the antidepressant effects, but not the receptors respon- sible for undesirable side effects. Another level of analysis regarding brain function is to study processing mediated by particular brain regions. The nervous system as a whole can be divided into two systems, the peripheral nervous system and the central nervous system. The peripheral nervous system conveys information to muscles, sensory receptors, and many organs. The peripheral nervous system comprises two major systems—the somatic nervous system, which largely is responsible for controlling voluntary move- ments, and the autonomic nervous system, which regu- lates many involuntary processes, such as heart rate and breathing. The autonomic nervous system comprises two systems, the parasympathetic nervous system and the sympathetic nervous system. The parasympathetic nervous system is typically ac tive when we are attempt- ing to increase the amount of energy stored. Thus, para- sympathetic nervous system activation can stimulate digestion and salivation. The sympathetic nervous sys- temiscriticalwhenweneedtoexpendenergyandis often referred to as being important for our fight-or- flight response, and thus performs functions such as increasing heart rate to increase blood flow to muscles. The central nervous system comprises the spinal cord and the brain. The brain can be divided into four lobes: 1. The occipital lobe, which is important for proces- sing visual information 2. The temporal lobe, which is important for processing auditory information and for some memory functions 3. The parietal lobe, which is involved in processing some spatial information and for integrating infor- mation from other brain areas 4. The frontal lobe, which is involved in processes including planning, working memory, and selec- tively attending to objects in our environment The outer 2–4 mm of the brain is grey matter, con- sisting mainly of cell bodies, known as the cortex. 726 Neuroscience A number of cortical regions have been identified, including cortical areas that process sensory informa- tion, such as for vision, audition, or olfaction. There are other cortical areas (and brain regions outside of the cortex) that engage our higher cognitive processes, such as planning, selectively attending to stimuli in the environment, or storing information in memory. Below the cortex is white matter, which primarily includes axons projecting to particular cortical regions. Addi- tionally, many subcortical brain regions, which are structures located below the cortex, are present. These structures include the thalamus, which, in part, relays information to cortical regions, and the hypothalamus, which maintains an organism’s homeostasis. There are brain regions toward the bac k of the head that contrib- ute to balance (the cerebellum) and that maintain many life-sustaining processes (the medulla). Although some specific processes can be associ- ated with some brain regions, contemporary neuro- science has demonstrated the importance of studying how brain systems, that is, interconnected brain regions, contribute to complex phenomena. For exam- ple, if you are at a stoplight, you must process the location and color of the light (as well as attend to the stoplight). Most likely, visual cortical brain regions will be important for this processing. However, you must also engage the rules for changing your behav- ior—take your foot off the brake and press the accel- erator when the light changes from red to green. This engagement of rules likely involves several cortical (and subcortical) regions, including the prefrontal cor- tex. The primary motor cortex or subcortical motor structures may be activated to cause your foot to move to the appropriate location as well as to receive proprioceptive feedback concerning how hard you are pressing. This example concerns a behavior that most drivers take for granted, yet gives at least some super- ficial indication of how several brain structures must work in a coordinated fashion to complete this task. Techniques Used in Neuroscience One of the most critical aspects to advancing our understanding of the brain is the development of tools to manipulate and measure brain functioning. This section highlights a few of these techniques, with an emphasis on comparing the relative advantages and disadvantages of different techniques. In humans, a number of noninvasive procedures can be employed to study neural functioning. One technique that has become prominently used is called functional mag- netic resonance imaging. This technique provides a measure of changes in blood oxygen levels to par- ticular brain regions. Increases in blood oxygen to a brain region are thought to reflect increased activity by that brain region. Magnetic resonance imaging offers impressive spatial resolution, that is, one is able to localize within the brain where the increase in blood oxygen flow occurs. The time course of this change in blood flow is at least a couple of seconds. In some instances, this temporal resolution may not be sufficient, and other techniques may need to be employed that allow measures to be taken more quickly. One approach for using this technique is to manipulate cognitive demands. For example, partici- pants could be asked to perform a working memory task or a similar task without a working memory requirement. One could then assess which brain regions show increases in blood oxygen levels during the working memory task, but not during the task with the working memory requireme nt removed. Ultimately, these data could provide information about the neural systems that are selectively activated during working memory. A procedure for measuring electrical activity from the scalp is electroencephalography. With this tech- nique, a cap containing electrodes is placed over spe- cific regions of the head. This procedure can measure the frequency of brain waves as well as changes in brain wave activity (termed event-related potentials ) in response to a stimulus. Electroencephalography offers temporal resolution on a millisecond scale, but it is difficult to localize the origins of the electrical signal. Thus, functional magnetic resonance imaging and electroencephalography differ in temporal and spatial resolution, leaving it to the researcher to deter- mine which technique is more appropriate for a partic- ular experiment. For more invasive procedures, humans can be injected with trace levels of radioac- tive ligands that bind to particular receptors in the brain. The amount of radioactivity can then be mea- sured, typically using a procedure known as positron emission tomography, to determine the number and efficacy of a particular receptor population. Animals can be used to test hypotheses about brain function. One traditional approach with animals is to damage a portion of the brain (or a particular popula- tion of neurons within a brain region) and assess changes in behavior. Lesion techniques can be used to understand whether a brain region is necessary for Neuroscience 727 some behavior or function. Thus, lesion techniques allow manipulation of the brain and assess changes in behavior or other aspects of brain functioning. How- ever, much like with humans, in some cases it is also desirable to assess the effects of manipulating behav- ior or cognitive processing demands (e.g., compare performance on a working memory task with a proce- dure that does not tax working memory) on brain function. Electrophysiology allows measures of the rate of action potentials from a neuron or small groups of neurons. Electrophysiology provides excel- lent temporal resolution, but it may be difficult to assess which neurotransmitter systems are leading to changes in neuronal firing rates. Microdialysisisaprocedureinwhichaprobewith asemipermeabletipisinsertedintoabrainregionand artificial cerebrospinal fluid is perfused through that brain region. Neurotransmitters can diffuse through the semipermeable membrane and be collected, and levels can be assessed using a procedure known as high- performance liquid chrom atography. Microdialysis does allow measurement of specific neurotransmitters, but often samples must be collected over at least 1 minute. Thus, microdialysis has a poorer temporal res- olution than electrophysiological techniques. Ulti- mately,itiscriticalforneur oscientists to ascertain the relative strengths and limitations of the techniques employed in an experiment. Such information is criti- cal for developing a clear interpretation about the effects of a manipulation on brain functioning. A number of techniques have been developed to study how genetics, including the expression of genes, contribute to brain function. Genes provide a code for specific proteins, and the regulation of these proteins can affect brain functioning. For example, genes can code for particular portions (called subunits) of a recep- tor. The type of subunit that is coded for can affect the overall activity of the neurot ransmitter system that acts at that receptor. One approach, gene microarrays, allows researchers to examine, from properly prepared brain tissue, the expression of thousands of genes from that tissue. Although microarrays are a powerful approach, it is possible that, with such a large number of genes being studied, some genes will demonstrate increased or decreased expression just by chance. Microarray analyses can provide a set of genes for future study, but additional approaches are important to further characterize the role of the expression of a specific gene in brain function. More targeted approaches include looking for a single change in the genetic code, known as a single nucleotide polymor- phism. The study of the role of gene expression in neuroscience has accelerated over the past 10 years, and techniques that assess many genes at once, as well as more targeted approaches that study a single gene, will be important in providing evidence to fur- ther the study of brain function. One goal within neuroscience is to understand relationships between brain and behavior or brain and underlying cognitive processes. To accomplish this goal, it is essential to have behavioral paradigms that assess the processes under study, in addition to sophisticated measures and manipulations of the brain. In humans, computer-controlled stimulus pre- sentation can be beneficial for standardizing experi- mental variables across laboratories as well as for carefully timed response measures. Numerous para- digms with animals have been developed to assess (among other processes) attention, working memory, anxiety-like behavior, and depressive-like behaviors. Some of these paradigms offer ‘‘artificial’’ labora- tory settings in which animals are rewarded for pressing a lever in response to a particular stimulus. Similar to human research with computers, these laboratory-based tasks offer consistency in experi- mental procedures across laboratories, thus faci- litating comparisons about research conducted in different laboratory environments. Typically, there are procedures employed to validate that a task is assessing the desired construct. For example, in a working memory task, performance would be expected to decrease as participants must remember information for a longer time period or when the number of items to be remembered is increased. The continued development of behavioral paradigms that allow specific assessment of behavior and/or cogni- tive processes is essential for neuroscience research aimed at understanding brain-behavior relationships. Neuroscience and Education How can neuroscience research contribute to educa- tion? One major goal of education, of course, is to increase knowledge and critical thinking. Behavioral neuroscience is a field dedicated to studying relation- ships between brain and behavior, including neural mechanisms underlying learning and memory. By understanding how the brain processes and stores information, educational programs can be developed that will provide material in a way that increases the 728 Neuroscience likelihood that the brain will be able to properly rec- ognize and recall that material. Neuroscience research can also help us to under- stand the development of brain regions and how that development may affect learning. For example, if we know that the prefrontal cortex develops later in ado- lescence, education programs that do not place heavy demands on prefrontal cortical processing may be ben- eficial. Conversely, it is also possible that educational programs that require prefrontal cortical processing may accelerate the development of this brain region. It is clear that the brain is a plastic organ that is continu- ously changing in terms of the strength of connections between different neurons. Education programs and neuroscience research could work together to learn more about strategies that stimulate brain development and about educational programs that may be more effective at different stag es of brain development. Developmental disorders can represent a significant challenge to successful education. One of the most common examples of such a disorder is attention deficit hyperactivity disorder (ADHD). Neuroscience research focuses on the changes in the brain using noninvasive techniques in humans or animal models. For example, individuals diagnosed with ADHD may perform a series of tasks while functional magnetic resonance imaging is employed to assess whether spe- cific brain regions show abnormally high or low blood flow levels compared with a control group. Based on animal models or positron emission tomography, in which individuals are injected with trace levels of radioactively labeled ligands, it is possible to assess whether particular neurotransmitter levels are elevated or decreased in individuals with ADHD. By using this approach, a pharmacological strategy can be developed to regulate neurotransmitter levels. Thus, neuroscience research can be used to try to improve traditional education programs and to treat some neu- ropsychological disorders that can impede classroom learning. One of the major challenges to education is that important social development is occurring that may assist or hinder learning. Furthermore, the educator may benefit from information about what types of material is better learned individually versus in a group setting. Traditionally, neuroscien ce has not focused heavily on social behavior; however, new fields are emerging, such as social neuroscience, that will provide information about how the brain responds to social interactions. A more complete understanding of the neural basis of social interactions may all ow educators to predict what types of materials may be learned well in a group set- ting as opposed to course information that may benefit from more individualized st udying. At the same time, for educators to receive maximum benefits from the tools and expertise of neuroscientists, it is essential that educators describe what types of information would be most useful to enhance student performance. Considerations Neuroscience is a discipline that ranges in study from the cells, neurons, which are responsible for much of the communication within the brain, to assessing the cognitive and behavioral consequences of brain damage. Given the range of approaches necessary for such diverse topics, it is not surprising that several subdisciplines have developed within neu- roscience. Furthermore, th e techniques necessary for breakthroughs in these subdisciplines are diverse, and the exact nature of what they are measuring needs to be considered carefully. A nother important consider- ation is that the different s ubdisciplines inform each other in order to characterize more fully brain function- ing. Such cross-disciplina ry approaches will provide more information about the neural mechanisms related to learning as well as for treating neuropsychological disorders that can disrupt learning. Joshua A. Burk See also Brain-Relevant Education; Dynamical Systems Further Readings Bechtel, W. (2002). Aligning multiple research techniques in cognitive neuroscience. Philosophy of Science , 69 , S48–S59. Cooper, J. R., Bloom, F. E., & Roth, R. H. (2003). The biochemical basis of neuropharmacology (8th ed.). New York: Oxford University Press. Posner, M. I., & DiGirolamo, G. J. (2000). Cognitive neuroscience: Origins and promise. Psychological Bulletin , 126 , 873–889. Society for Neuroscience. (2003). Translational neuroscience accomplishments. Retrieved from http://www.sfn.org/ skins/main/pdf/gpa/translational.pdf Squire, L. R., Bloom, F. J., McConnell, S. K., Roberts, J. L., Spitzer, N. C., & Zigmond, M. (2003). Fundamental neuroscience (2nd ed.). San Diego, CA: Elsevier Science. Neuroscience 729 N O C HILD L EFT B EHIND On January 8, 2002, President George W. Bush signed the No Child Left Behind (NCLB) Act into law. No Child Left Behind was a comprehensive, complex, and controversial education law that was passed as a reaction to the low academic achievement, espe- cially reading achievement, exhibited by many pub- lic school students in the United States. The law represented an unprecedented increase in the role that the federal government plays in education because the law dramatically increased federal mandates and requirements on states, school districts, and public schools. The NCLB also increased federal funding to states by almost 25 % . The law affected all students who attended public schools by requiring states and public schools to be held accountable for improving student achievement in reading and math. Moreover, NCLB required that educators use scientifically based strategies and methods, which represent the primary tools that will allow schools to make meaningful changes in the academic achievement of their stu- dents. This entry begins with a brief description of the history of NCLB and describes the major components of the law. History No Child Left Behind was the most recent reauthori- zation of the Elementary and Secondary Education Act (ESEA) of 1965. The ESEA was passed as part of President Lyndon Johnson’s War on Poverty. The law appropriated federal money for states to improve educational opportunities for disadvantaged children. Although Congress allocates funds to the ESEA annually, Congress must reauthorize the law every 5 or 6 years. In 1994, the bill that reauthorized the ESEA was titled the Improving America’s Schools Act (IASA). The central purpose of IASA was to implement standards-based education throughout the nation. The IASA created a new framework for the federal role in elementary and secondary education, in which the federal government not only provided aid to schools serving economically disadvantaged students but extended federal support to the states’ implementation of local and state standards-based reform. The IASA was based on states’ developing challenging academic standards, creating and aligning assessments for all students, holding schools accountable for results, and increasing aid to high-poverty schools. The 2001 reauthorization of the ESEA was titled NCLB. The passage of NCLB expanded the role of the federal government in public education by holding states, school districts, and schools accountable for producing measurable gains in students’ achievement in reading and mathematics. For the first time, the federal government in NCLB began requiring states and school districts to use numerical data to provide evidence of improved student outcomes. Purpose The primary purpose of NCLB was to ensure that stu- dents in every public school achieve important learn- ing goals while being educated in safe classrooms by well-prepared teachers. To increase student achieve- ment, the law required that school districts (a) assume responsibility for all their students reaching certain goals in reading and math, (b) use scientifically based procedures to teach reading and math, and © have highly qualified teachers in all their classrooms. Furthermore, NCLB required schools to close academic gaps between economically advantaged students and students who are from differ ent economic, racial, and ethnic backgrounds as well as students with disabilities. TheprimarygoalsofNCLBwerethat • All students will achieve high academic standards, by attaining proficiency or better, in reading and mathematics by the 2013–2014 school year. • Highly qualified teachers will teach all students by the 2005–2006 school year. • All students will be educated in schools and class- rooms that are safe, drug free, and conducive to learning. • All limited-English-proficient students will become proficient in English. • All students will graduate from high school. Major Principles Accountability for Results No Child Left Behind focused on accountability for results in three major ways. First, the law required states to first identify the most important academic content for students to learn. Second, NCLB required that states adopt or develop statewide assessments that were aligned to the state standards in reading-language arts, math, and 730 No Child Left Behind eventually science. Third, states were required to set pro- ficiency standards, which were goals that schools and school districts had to attain within certain periods of time in order to have 100 % of their public school students scoring proficient or above on the statewide tests of read- ing and math by the 2013–2014 school year. Statewide Academic Achievement Standards. No Child Left Behind required s tates to identify important academic content for students to learn. Specifically, the law required states to develop academic standards for all students in reading-language arts, math, and science. States were free to develop standards in other areas, too. The purpose of the state-defined standards was to pro- vide guidelines to schools, par ents, and teachers that tell them what achievement will be expected of all students. Statewide Assessments. No Child Left Behind required that states adopt or develop s tatewide assessments that were aligned to the state standards in reading-language arts, math, and eventually science. The purpose of the statewide testing was to measure how successfully stu- dents were learning what was expected of them and how they were progressing toward meeting these important academic standards. States were required to assess students’ knowledge and skills in reading and math in Grades 3 through 8. The purpose of the state tests was to enable stakeholders (e.g., tea- chers, administrators, parents, policymakers, and the general public) to understand and compare the per- formances of schools against the standards for profi- ciency as set by the states. The results of these assessments were to be reported to parents in annual report cards. This information would tell parents about where their child stood academically and if their child’s school and school district were succeed- ing in meeting state standards. Thus, these assess- ments were used to hold schools accountable for the achievement of all students. Adequate Yearly Progress. States were required to set proficiency standards, which were goals that schools and school districts had to a ttain within certain periods of time in order to have 100 % of their public school students scoring proficient or above on the statewide tests of reading and math by the 2013–2014 school year. In addition to all students in a school, schools also were to test and report on the performance of the following subgroups: students who were economically disadvantaged, students fro m racial and ethnic groups, students with disabilities, and students with limited English proficiency. These goals or targets represented percentages of students who achieved proficiency on the statewide tests in readi ng and mathematics. Schools had to make these targets in order to achieve adequate yearly progress (AYP). States were responsible for determining their own system of requirements and rewards to hold all public schools and school district s responsible for meeting AYP. For example, if a school met its AYP target, it could be designated a ‘‘Distinguished School.’’ If a school failed to meet its AYP target, the school was to receive assistance from the state to improve its scores. When a school was first identified for improvement, the state provided technical assistance to enable the school to address the specific problems that led to its being iden- tified. The school, in conjunction with parents and out- side experts, had to develop a 2-year improvement plan. No Child Left Behind also had very specific requirements for schools that did not make AYP. If a school did not make AYP, this information had to be published and disseminated to parents, teachers, and the community in an easy-to-understand format. Schools that did not make AYP for 2 consecutive years were designated in need of improvement. In such situations, the state needed to continue to pro- vide technical assistance to the school. Additionally, the school had to offer the parents of students in the designated school the option of transferring to another public school within the district. This option was called public school choice. For schools that contin- ued to fail to make AYP, NCLB required that schools take the following actions: 1. Three consecutive years: In addition to continuing to offer public school choice, the school district had to offer supplemental services to disadvantaged students. 2. Four consecutive years: In addition to continuing to offer public school choice and supplemental educa- tion services, the school was required to implement corrective actions to improve the school, such as • replacing certain staff responsible for failure to make AYP, • implementing a new curriculum grounded in scientifically based research, • hiring outside experts to assist the school, and • reorganizing the management structure. 3. Five consecutive years: In addition to the above, the school had to be restructured by taking actions such as No Child Left Behind 731 • replacing the staff, • contracting with a private firm to run the school, and • reopening the school as a charter school. If these procedures are not successful, the state may take over management of the school district. Schools that are in need of improvement can be removed from that category if the school makes AYP for 2 consecutive years. Scientifically Based Instruction The second major principle of NCLB required that states and school districts use scientifically based instructional programming to improve the achievement of students. The authors of NCLB believed that, too often, schools had adopted pro- grams and practices that were not effective, which would result in lower academic achievement. No Child Left Behind emphasized using educational programs and practices that had been demonstrated to be effective by rigorous scientific research. A central principle in NCLB, therefore, required that federal funds be expended to support only educa- tional activities that were supported by scientifically based research evidence that the procedures actually increased student achievement. The intent of NCLB is to require that rigorous standards be applied to educational research and that research-based instruction is used in classroom set- tings. This means that state and local educational agencies must pay attention to research in education and ensure that teachers use evidence-supported meth- ods in their classrooms. The National Research Council reported that for a research design to be scientific, it must allow for direct, experimental investigation of important educa- tional questions. No Child Left Behind defined scientif- ically based research as ‘‘research that applies rigorous, systematic, and objective procedures to obtain relevant knowledge’’ (NCLB x 1208(6)). This includes research that (a) uses systematic, empirical methods that draw on observation or experime nt; (b) involves rigorous data analyses that are adequate to state hypotheses and justify the conclusions; © relies on measurement or observational methods that provide valid data for evalua- tors and observers and across multiple measures and observations; and (d) has been accepted by a peer- reviewed journal or approved by a panel of independent experts through a comparably rigorous, objective, and scientific review. Highly Qualified Teachers The authors of NCLB believed that the quality and skill of a student’s teacher are extremely important factors in student achievement. Congress recognized the importance of having well-prepared teachers in public school classrooms when they included provi- sions in the NCLB requiring that all new teachers hired in programs supported by Title 1 funds had to be highly qualified teachers beginning with the 2002–2003 school year. Additionally, the law required that by the end of the 2005–2006 school year, all tea- chersinpublicschoolshadtobehighlyqualified.The NCLB also requires that states ensure that paraprofes- sionalswhoworkinthenation’sclassroomsmustalso be highly qualified. There are three basic requirements in the NCLB that public school teachers must meet to be highly qualified. First, teachers must hold a minimum of a bachelor’s degree from a college or university. Second, teachers must have full state teacher certification or licensure for the area in which they teach. Third, teachers must be able to demonstrate subject matter competency in the core academic subjects in which they teach. Tea- chers can demonstrate subject matter competence by passing a state-administered test in each of the core sub- jects that he or she teaches. The structure and content of these tests are determined by the individual states. To ensure that only highly qualified teachers teach in public school classrooms, each state receiving funds under Title 1 of NCLB must develop a plan to ensure that all of the state’s public school teachers are highly qualified to teach core academic subjects in which they provide instruction. The NCLB regulations defined core academic subjects as English, reading- language arts, mathematics, science, foreign languages, civics, government, economics, art, history, and geog- raphy. If a teacher taught in one of these core subjects, the NCLB highly qualified requirement applied to him or her. If a teacher taught in more than two of these core subjects, he or she had to be qualified in all of the subject areas taught. In summary, NCLB was a complex, sweeping, and controversial law that was passed as a reaction to the low academic achievement exhibited by many public school students in America. NCLB held states, school districts, principals, and teachers accountable 732 No Child Left Behind for making meaningful improvements in students’ aca- demic performance. No Child Left Behind also points educators toward the tool that will allow schools to make meaningful changes in the academic achievement of their students: scientifically based research. Mitchell Yell See also Individual Differences; Individuals with Disabilities Education Act; Learning Style Further Readings Caterino, L. C. (2007). Review of assessment accommodations for diverse learners. Journal of Psychoeducational Assessment , 25 , 206–208. Charles, M. T. (2004). Where are we going as we leave no child behind? La technique and Postman, Papert, and Palmer—Part One by Michael T. Charles. Retrieved July 10, 2007, from http://bcis.pacificu.edu/journal/2004/01/ charles.php The White House. (2001). No Child Left Behind. Retrieved July 10, 2007, from https://www.whitehouse.gov/news/ reports/no-child-left-behind.pdf N ORMAL C URVE The normal distribution is one of the most important probability distributions in statistics in that many sta- tistical analyses build on the assumption that the data follow the normal distribution, and in that many phys- ical and biological phenomena in real life can be approximated by the normal distribution. A normal distribution is specified by two para- meters: mean µ and standard deviation σ . If a random variable X follows the normal distribution with mean µ and standard deviation σ , it is often denoted by X ∼ N ð µ , σ 2 Þ . The normal distribution has a bell shape as shown below, which is called the normal curve. Technically, the normal curve is given by the fol- lowing formula: f ( x ) = 1 σ ffiffiffiffiffiffi 2 π p exp − ( x − µ ) 2 2 σ 2 : The variable x takes any real value. The mean µ specifies the central location of the distribution, and the standard deviation σ determines to what extent the distribution is spread out. The curve has a maximum height at x = µ and is symmetric about µ.Inprobabi- listic terms, the normal curve represents the probabil- ity density function of the normal distribution; the height of the curve at each point of x denotes the cor- responding probability density. The most important characteristic of a probability density function is that an area under the curve on a specified interval taken on the x -axis represents a probability that the random variable takes values within that interval. In the case of the normal distribution, as shown in Figure 1, the probability that X is within one standard deviation from the mean is approximately 68.2 % ,andtheprob- ability that X is within two standard deviations from the mean is approximately 95.4 % . Especially if µ = 0and σ = 1, the distribution is called the standard normal distribution , which is fre- quently used as the reference distribution in statistical testing. A probability table for the standard normal distribution is usually provided in standard statistics textbooks. Any random variable that follows an arbi- trary normal distribution can be transformed to the standard normal by subtracting the mean and then dividing by the standard deviation. In other words, if X ∼ N ( µ , σ 2 ), then ( X - µ )/ σ ∼ N (0, 1). Thus, proba- bility values for any normal distribution can be referred to in a probability table for the standard nor- mal distribution. The central limit theorem exemplifies the theoreti- cal importance of the normal distribution. Suppose that you take a random sample of size n from an arbi- trary distribution and compute the me
