Introduction to Cognitive Psychology Chapter 1 PDF

20 CHAPTER 1 Introduction to Cognitive Psychology CONTROLLED SELF-REPORTS, SUCH...

20 CHAPTER 1 Introduction to Cognitive Psychology CONTROLLED SELF-REPORTS, SUCH NEUROSCIENTIFIC ME METHOD METHOD LABORATORY RESEARCH AS VERBAL PROTOCOLS, EXPERIMENTS SELF-RATINGS, DIARIES Random assignment of subjects Usually Not usually Not applicable Experimental control of Varies widely, depending Usually Probably not independent variables on the particular technique Sample size May be any size Often small Probably small Sample May be representative Often not representative May be representative representativeness Not unlikely; depends on the Unlikely under some Maybe; see strengths Ecological validity task and the context to which circumstances and weaknesses it is being applied Information about Usually de-emphasized Yes Yes individual differences Easy to administer, score, Provides “hard” evidence Access to introspective and statistically analyze of cognitive functions insights from participants’ High probability of drawing Alternative view of cognitive point of view valid causal inferences processes Strengths Possibility to develop treatments for cognitive deficits Difficulty in generalizing Limited access to appropriate Inability to report on results beyond a specific subjects and expensive processes occurring outside place, time, and task setting equipment (for most conscious awareness Discrepancies between researchers) Verbal protocols and self- behavior in real life and in Small samples ratings: May influence Weaknesses the laboratory cognitive process being Decreased generalizability when abnormal brains or reported animal brains are Discrepancies between investigated actual cognition and recollected cognitive processes and products Karpicke (2009) developed a New and colleagues (New et In a study about the relation laboratory task in which al., 2009) have found that between cortisol levels (which participants had to learn and borderline patients with are stress-dependent) and recall Swahili-English word Intermittent Explosive sleep, self-rated health, and pairs. After subjects first Disorder responded more stress, participants kept recalled the meaning of a aggressively to a provocation diaries and collected saliva word, that pair was either than did normal control samples over four weeks Examples dropped, presented twice subjects. The patients (Dahlgren et al., 2009). more in a study period, or particularly show an increase presented twice more in text in glucose consumption in periods. Subjects took a final brain areas associated with recall test one week later. emotion like the amygdala and less activity in dorsal brain regions that serve to control aggression. Figure 1.6 Research Methods. Cognitive psychologists use controlled experiments, neuroscientific research, self-reports, case studies, naturalistic observation, and computer simulations and artificial intelligence when studying cognitive phenomena. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Introduction to Cognitive Psychology CHAPTER 1 21 Doe COMPUTER SIMULATIONS John John Doe NATURALISTIC CP CASE STUDIES AND U OBSERVATIONS ARTIFICIAL INTELLIGENCE Highly unlikely Not applicable Not applicable Highly unlikely Full control of No variables of interest Almost certain to be small Probably small Not applicable Not likely to be representative May be representative Not applicable High ecological validity for individual cases; lower Yes Not applicable generali ability to others Possible, but emphasis is on Yes; richly detailed information Not applicable environmental distinctions, regarding individuals not on individual differences Access to detailed information Access to rich contextual Exploration of possibilities for about individuals, including information modeling cognitive processes historical and current contexts Allows clear hypothesis testing ay lead to speciali ed ide range of practical applications for special groups applications (e.g., robotics for (e.g., prodigies, persons with performing dangerous tasks brain damage) Applicability to other persons Lack of experimental control Limitations imposed by the Limited generali ability due to Possible influence on hardware (i.e., the computer small sample si e and behavior due to presence circuitry) and the software (i.e., nonrepresentativeness of of observer the programs written by the sample researchers) Simulations may imperfectly model the way that the human brain thinks A case study with a breast A study using questionnaires Simulations: Through detailed cancer patient showed that a and observation found that computations, David Marr (1982) new technique (problem- exicans on average attempted to simulate human solving therapy) can reduce consider themselves less visual perception and proposed a anxiety and depression in sociable than U.S. Americans theory of visual perceptions based cancer patients (Carvalho & consider themselves; on his computer models. Hopko, 2009). however exicans behave Al: Various AI programs have much more sociably than U.S. been written that can demonstrate Americans in their everyday expertise (e.g., playing chess), lives (Ramire -Espar a et al. but they probably do so via 2009). different processes than those used by human experts. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 22 CHAPTER 1 Introduction to Cognitive Psychology your experimental group, but no such people in your control group. If those requisites for the experimental method are fulfilled, the experimenter may be able to infer prob- able causality. That is, the researcher can infer how likely it is that the effect of the inde- pendent variable or variables (the treatment) on the dependent variable (the outcome) is not a result merely of chance, at least for the given population. in the lab of HENRY L. ROEDIGER, III The Science of the Mind In 1620 Sir Francis Bacon wrote, “If you read a piece the quotation after the studies were well under way). of text through twenty times, you will not learn it In our experiments, students learn materials (either by heart so easily as if you read it ten times while simple sets of words or more complex text book pas- attempting to recite from time to time and consulting sages—the material does not matter) by various com- the text when your memory fails.” How did he know binations of studying and testing the material. The that? The answer is that he did not know, for sure, but general finding is that retrieval (or reciting, as Bacon based his judgment on his own personal experience. called it) during a test provides a great boost to later The case is interesting because Bacon was one of the retention, much more so than repeated studying originators of the scientific method and laid out the (Roediger & Karpicke, 2006; see Roediger & Butler, framework for experimental science. 2011 for a review). Science in Bacon’s time was Let us consider just one experi- applied to the natural world, what ment here to make the point. Zaromb today would be called the physical sci- and Roediger (2010) gave students ences (chiefly, physics and chemistry). lists of words to remember in prepa- The idea that scientific methods could ration for a test that would be given be applied to people was not even two days later. Students in one condi- dreamt of and, had the notion been tion studied the material eight times raised, it would have been hooted with short breaks, but students in Courtesy of the author down. Human beings were not dross two other conditions received either stuff; they had souls, they had free two or four tests in place of some of will—surely they could not be studied the study trials. If S denotes a study scientifically! It took another 250 years trial and T denotes a test (or recita- before pioneers would question this Henry L. Roediger, III tion), the three conditions can be assumption and take the brave step labeled SSSSSSSS, STSSSTSS, or to create a science of psychology, the STSTSTSTST. If studying determines study of the mind. The date usually given is 1879, later recall, then the three conditions just listed should when Wilhelm Wundt founded the first psychology be ordered in terms of decreasing effectiveness (from laboratory in Leipzig, Germany. eight to six to four study trials). If Bacon is right, how- Edwin G. Boring, the great historian of psychol- ever, the conditions should be ordered in increasing ogy, wrote that the “application of the experimental effectiveness for later retention (from zero to two to method to the problem of mind is the great outstand- four test trials). The result: the proportion recalled two ing event in the study of the mind, an event to which days later was 0.17, 0.25 and 0.39 for the three condi- no other is comparable” (1929, p. 659). Boring is right, tions in the order listed previously. and the textbook you hold relates the fascinating Sir Francis Bacon was right: Reciting is more effec- story of cognitive psychology, today’s experimental tive than studying (although of course some study- study of mind. ing is required). To my knowledge, no one has done But what about Bacon’s assertion? Does reciting the actual experiment he suggested (20 trials), but it material really help one learn it more than studying it? would make a fine class project with 20 study trials This idea seems odd because in education we think for one condition or 10 study and 10 test trials for the of studying as being how we learn, and we think of other. By the way, self-testing on material is a good testing as only measuring what has been learned. way to study for your courses. In our book, Make It My students and I have been studying the pos- Stick: The Science of Successful Learning, we sug- sible validity of Bacon’s claim in a variety of experi- gest many other strategies for enhancing learning mental contexts (although, truth be told, we found (Brown, Roediger, & McDaniel, 2014). Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 37 Joe Petersburger / Getty images Figure 2.1 The Brain. What does a brain actually look like? Here you can see a side view of a human brain. Subsequent figures detail some of the main features of the brain. (Gloor, 1997; Rockland, 2000; Shepherd, 1998). Figure 2.1 shows photos of what the brain actually looks like. We usually think of the brain as being at the top of the body’s hierarchy—as the boss, with various other organs responding to it. Like any good boss, however, it listens to and is influenced by its subordinates, the other organs of the body. Thus, the brain is reactive as well as directive. A major focus of brain research is localization of function. Localization of func- tion refers to the specific areas of the brain that control specific skills or behaviors. Facts about particular brain areas and their function are interspersed throughout this chapter and also throughout the whole book. Our exploration of the brain starts with the anatomy of the brain. We will look at the gross anatomy of the brain as well as at neurons and the ways in which information is transmitted in the brain. Then we will explore the methods scientists use to examine the brain, its structures, and its functions. And finally, we will learn about brain disorders and how they inform cognitive psychology. Cognition in the Brain: The Anatomy and Mechanisms of the Brain The nervous system is the basis for our ability to perceive, adapt to, and interact with the world around us (Gazzaniga, 1995b, 2000; Gazzaniga, Ivry, & Mangun, 2014). The brain is the supreme organ of the nervous system. The part of the brain that controls many of our thought processes is the cerebral cortex. Let’s have a look at the structure of the brain. Gross Anatomy of the Brain: Forebrain, Midbrain, and Hindbrain What have scientists discovered about the human brain? The brain has three major regions: forebrain, midbrain, and hindbrain. These labels do not correspond exactly to locations of regions in an adult or even a child’s head. Rather, the terms come from the front-to-back physical arrangement of these parts in the nervous system of a developing Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 38 CHAPTER 2 Cognitive Neuroscience Cerebellum Midbrain Midbrain Hindbrain Forebrain Pons Hindbrain Medulla Forebrain Cranial nerves Spinal cord (a) 3 weeks (b) 7 weeks Midbrain Forebrain Forebrain Cerebellum Cerebral hemisphere Hindbrain Medulla Cerebellum Midbrain Medulla Pons (hidden) (c) 11 weeks (d) At birth Figure 2.2 Fetal Brain Development. Over the course of embryonic and fetal development, the brain becomes more highly specialized and the locations and relative positions of the hindbrain, the midbrain, and the forebrain change from conception to term. Source: Adapted from In Search of the Human Mind by Robert J. Sternberg, 1995 by Harcourt Brace & Company. embryo. Initially, the forebrain is generally the farthest forward, toward what becomes the face. The midbrain is next in line. And the hindbrain is generally farthest from the forebrain, near the back of the neck [Figure 2.2(a) ]. As the fetus develops, the relative orientations change so that the forebrain is almost a cap on top of the midbrain and hindbrain. Figures 2.2(b) , 2.2(c) , and 2.2(d) show the changing locations and relationships of the forebrain, the midbrain, and the hindbrain over the course of devel- opment of the brain. You can see how they develop, from an embryo a few weeks after conception to birth. The Forebrain The forebrain is the region of the brain located toward the top and front of the brain. It includes the cerebral cortex, the basal ganglia, the limbic system, the thalamus, and the hypothalamus (Figure 2.3 ). The cerebral cortex is the outer layer of the cerebral hemi- spheres. It plays a vital role in our thinking and other mental processes. It therefore merits a special section in this chapter, which follows the present discussion of the major struc- tures and functions of the brain. The basal ganglia (singular: ganglion) are collections of neurons crucial to motor function. Dysfunction of the basal ganglia can result in motor deficits. These deficits include tremors, involuntary movements, changes in posture and muscle tone, and slowness of movement. Deficits are observed in Parkinson’s disease and Huntington’s disease. Both of these diseases entail severe motor symptoms (Gutierrez- Garralda et al., 2013; Lerner & Riley, 2008; Lewis & Barker, 2009; Rockland, 2000). Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 39 Hippocampus Cerbral cortex Basal ganglia Forebrain Corpus callosum Septum Thalamus Hypothalamus Midbrain Amygdala Pons Brainstem Cerebellum Medulla Hindbrain oblongata Pituitary gland Spinal cord Figure 2.3 Structures of the Brain. The forebrain, the midbrain, and the hindbrain contain structures that perform essential functions for survival and for high-level thinking and feeling. Source: Adapted from Psychology: In Search of the Human Mind by Robert J. Sternberg, 2000 by Harcourt Brace & Company. The limbic system is important to emotion, motivation, memory, and learning. Animals such as fish and reptiles, which have relatively undeveloped limbic systems, respond to the environment almost exclusively by instinct. Mammals and especially humans have more developed limbic systems. Our limbic system allows us to suppress instinctive responses (e.g., the impulse to strike someone who accidentally causes us pain). Our limbic systems help us adapt our behaviors flexibly in response to our chang- ing environment. The limbic system comprises three central interconnected cerebral structures: the septum, the amygdala, and the hippocampus. The septum is involved in anger and fear (Breedlove & Watson, 2013). The amyg- dala plays an important role in emotion as well, especially in anger and aggression (Adolphs, 2003; Derntl et al., 2009). Stimulation of the amygdala commonly results in fear. It can be evidenced in various ways, such as through palpitations, fearful hal- lucinations, or frightening flashbacks in memory (Engin & Treit, 2008; Gloor, 1997; Rockland, 2000). Damage to (lesions in) or removal of the amygdala can result in maladaptive lack of fear. In the case of lesions to the animal brain, the animal approaches potentially dangerous objects without hesitation or fear, or can no longer adequately learn fear reac- tions when it encounters dangerous situations (Adolphs et al., 1994; Frackowiak et al., 1997; Kazama et al., 2012). The amygdala also enhances the perception of emotional stimuli. If someone has a lesion in his or her amygdala, the perception of emotional stimuli is impaired (Anderson & Phelps, 2001; Tottenham, Hare, & Casey, 2009). For Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 40 CHAPTER 2 Cognitive Neuroscience example, when people are presented with a number of words and then have to remem- ber them, they usually remember negative words (such as murder) better than neutral words. In people with lesions to the amygdala, this is not the case. Additionally, people with autism display limited activation in the amygdala. A well-known theory of autism suggests that the disorder involves dysfunction of the amygdala, which leads to the social impairment that is typical of persons with autism, for example, difficulties in evaluat- ing people’s trustworthiness or recognizing emotions in faces (Adolphs, Sears, & Piven, 2001; Baron-Cohen et al., 2000; Howard et al., 2000; Kleinhans et al., 2009). Two other effects of lesions to the amygdala can be visual agnosia (inability to recognize objects) and hypersexuality (Steffanaci, 1999). The hippocampus is essential in memory formation (Eichenbaum, 1999, 2002, 2011; Gluck, 1996; Manns & Eichenbaum, 2006; O’Keefe, 2003). It gets its name from the Greek word for “seahorse,” its approximate shape. The hippocampus is essential for flexible learning, seeing relationships among items learned and spatial memory (Eichenbaum, 1997; Forcelli et al., 2014; Kaku, 2014; Squire, 1992). The hippocampus also appears to keep track of where things are and how these things are spatially related to each other. In other words, it monitors what is where (Cain, Boon, & Corcoran, 2006; Howland et al., 2008; McClelland et al., 1995; Tulving & Schacter, 1994). We return to the role of the hippocampus in Chapter 5. People who have suffered damage to or removal of the hippocampus still can recall existing memories—for example, they can recognize old friends and places—but they are unable to form new memories (relative to the time of the brain damage). New information—new situations, people, and places—remains forever new. A disease that produces loss of memory function is Korsakoff ’s syndrome. Other symptoms include apathy, paralysis of muscles controlling the eye, and tremor. This loss is believed to be associated with deterioration of the hippocampus and is caused by a lack of thiamine (vitamin B-1) in the brain. The syndrome can result from excessive alcohol use, dietary deficiencies, or eating disorders. There is a renowned case of a now-deceased patient known as H. M. (but whose real name was Henry Molaison), who after brain surgery retained his memory for events that transpired before the surgery but had no memory for events after the surgery. This case is another illustration of memory problems forming because of hippocampus damage (see Chapter 5 for more on H. M.). Disruption in the hippocampus appears to result in defi- cits in declarative memory (i.e., memory for pieces of information), but it does not result in deficits in procedural memory (i.e., memory for courses of action; Rockland, 2000). The thalamus relays incoming sensory information through groups of neurons that project to the appropriate region in the cortex. Most of the sensory input into the brain passes through the thalamus, which is approximately in the center of the brain, at about eye level. To accommodate all of the types of information that must be sorted out, the thalamus is divided into a number of nuclei (groups of neurons of similar func- tion). Each nucleus receives information from specific senses. The information is then relayed to corresponding specific areas in the cerebral cortex. The thalamus also helps in the control of sleep and waking. When the thalamus malfunctions, the result can be pain, tremor, amnesia, impairment of language, and disruptions in waking and sleeping (Cipolotti et al., 2008; Rockland, 2000; Steriade, Jones, & McCormick, 1997). In cases of schizophrenia, imaging and in vivo studies reveal abnormal changes in the thalamus (Clinton & Meador-Woodruff, 2004). These abnormalities result in difficulties in filter- ing stimuli and focusing attention, which in turn can explain why people suffering from schizophrenia experience symptoms such as hallucinations and delusions. The hypothalamus regulates behavior related to species survival: fighting, feeding, fleeing, and mating. The hypothalamus also helps regulate emotions and react to stress Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 41 (Malsbury, 2003). It interacts with the limbic system. The small size of the hypothalamus (from Greek hypo-, “under”; located at the base of the forebrain, beneath the thalamus) belies its importance in controlling many bodily functions (Table 2.1 ). The hypothal- amus plays a role in sleep: Dysfunction and neural loss within the hypothalamus are Ta b l e 2. 1 Major Structures and Functions of the Brain Region of the Brain Major Structures within the Regions Functions of the Structures Forebrain Cerebral cortex (outer layer of the cere- Involved in bral hemispheres) receiving and processing sensory information, thinking and other cognitive processing, and planning and sending motor information Basal ganglia (collections of nuclei and Crucial to the function of the motor system neural fibers) Limbic systems (hippocampus, amyg- Involved in learning, emotions, and motivation dala, and septum) Thalamus Transmits sensory information coming to the cerebral cortex; includes several nuclei (groups of neurons) specializing in perception of visual stimuli, auditory stimuli, pressure and pain, and information that helps us sense physical balance and equilibrium Hypothalamus Involved in the endocrine system; autonomic nervous system; survival behavior (e.g., fighting, feeding, flee- ing, and mating); consciousness; and emotions, pleasure, pain, and stress reactions Midbrain Superior colliculi (on top) Involved in vision (especially visual reflexes) Inferior colliculi (below) Involved in hearing Reticular activating system (also extends Important in controlling into the hindbrain) consciousness (sleep arousal), attention, cardiorespiratory function, and movement Gray matter, red nucleus, substantia Important in controlling movement nigra, and ventral region Hindbrain Cerebellum Essential to balance, coordination, and muscle tone Pons (also contains part of the reticular Involved in activating system) consciousness, facial nerves, and bridging neural transmissions from one part of the brain to another Medulla oblongata Nerves cross here from one side of the body to opposite side of the brain; involved in cardiorespi- ratory function, digestion, and swallowing Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 42 CHAPTER 2 Cognitive Neuroscience noted in cases of narcolepsy, whereby a person falls asleep often and at unpredictable times (Lodi et al., 2004; Mignot, Taheri, & Nishino, 2002). The hypothalamus also is important for the functioning of the endocrine system. It is involved in stimulating the pituitary glands, through which a range of hormones are produced and released (Gaz- zaniga, Ivry, & Mangun, 2013). Structures in the forebrain, midbrain, and hindbrain perform functions essential for survival as well as for high-level thinking and feeling. For a summary of the major structures and functions of the brain, as discussed in this section, see Table 2.1. The Midbrain The midbrain helps to control eye movement and coordination. Table 2.1 lists several structures and corresponding functions of the midbrain. By far the most indispensable of these structures is the reticular activating system (RAS). Also called the “reticu- lar formation,” the RAS is a network of neurons essential to regulating consciousness, including sleep; wakefulness; arousal; attention to some extent; and vital functions, such as heartbeat and breathing (Sarter, Bruno, & Berntson, 2003). The RAS also extends into the hindbrain. Both the RAS and the thalamus are essen- tial to our conscious awareness of or control over our existence. The hindbrain, along with the thalamus, midbrain, and hypothalamus, make up the brainstem, which con- nects the forebrain to the spinal cord. Physicians make a determination of brain death based on the function of the brain- stem. Specifically, a physician must determine that the brainstem has been damaged so severely that various reflexes of the head (e.g., the pupillary reflex) are absent for more than 12 hours, or the brain must show no electrical activity or cerebral circulation of blood (Berkow, 1992; Shappell et al., 2013). The Hindbrain The hindbrain comprises the medulla oblongata, the pons, and the cerebellum. The medulla oblongata controls heart activity and largely controls breathing, swallowing, and digestion. The medulla is also the place at which nerves from the right side of the body cross over to the left side of the brain and nerves from the left side of the body cross over to the right side of the brain. The medulla oblongata is an elongated interior structure located at the point at which the spinal cord enters the skull and joins with the brain. The medulla oblongata, which contains part of the RAS, helps to keep us alive. The pons contains neural fibers that pass signals from one part of the brain to another. Its name derives from the Latin for “bridge,” as it serves a bridging function. The pons also contains a portion of the RAS and nerves serving parts of the head and face. The cerebellum (from Latin, “little brain”) controls bodily coordination, balance, and muscle tone, as well as some aspects of memory involving procedure-related move- ments (see Chapters 7 and 8) (Middleton & Helms Tillery, 2003). The prenatal develop- ment of the human brain roughly corresponds to the evolutionary development of the human brain within the species as a whole. Specifically, the hindbrain is evolutionarily the oldest and most primitive part of the brain. It also is the first part of the brain to develop prenatally. The midbrain is a relatively newer addition to the brain in evolution- ary terms. It is the next part of the brain to develop prenatally. Finally, the forebrain is the most recent evolutionary addition to the brain. It is the last of the three portions of the brain to develop prenatally. For cognitive psychologists, the most important of these evolutionary trends is the increasing neural complexity of the brain. The evolution of the human brain has offered Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 43 us the enhanced ability to exercise voluntary control over behavior. It has also strength- ened our ability to plan and to contemplate alternative courses of action. These ideas are discussed in the next section with respect to the cerebral cortex. in the lab of MARTHA FARAH Cognitive Neuroscience and Childhood Poverty Around the time I had my daughter, I shifted my first graders and in middle school students, we again research focus to developmental cognitive neurosci- found striking SES disparities in language and execu- ence. People naturally assumed that tive function, as well as in declarative these two life changes were related, and memory. Assuming that these dispari- they were—but not in the way people ties are the result of different early life thought. What captured my interest in experiences, what is it about growing brain development was not principally up poor that would interfere with the watching my daughter grow, as won- development of these specific systems? drous a process as that was. Rather, In one study, we made use of data Courtesy of the author it was getting to know the babysitters collected earlier on the middle school who entered our lives, and learning children just mentioned. We found that about theirs. their language ability in middle school These babysitters were young was predicted by the amount of cogni- women of low socioeconomic status tive stimulation they experienced as Martha Farah (SES), who grew up in families depen- 4-year-olds—being read to, being taken dent on welfare and supported their own on trips, and so on. In contrast, we found that young children with a combination of state assistance their declarative memory ability in middle school was supplemented with cash wages from babysitting. As predicted by the quality of parental nurturance that caregivers for my child, they were not merely hired they received as young children—being held close, help; they were people I liked, trusted, and grew to being paid attention to, and so on. The latter finding care about. And as we became closer, and I spent might seem an odd association. Why would affec- more time with their families, I learned about a world tionate parenting have anything to do with memory? very different from my own. Yet research with animals shows that when a young The children of these inner city families started animal is stressed the resulting stress hormones can life with the same evident potential as my own child, damage the hippocampus, a brain area important for learning words, playing games, asking questions, and both stress regulation and memory. This research has grappling with the challenges of cooperation, disci- also shown that more nurturing maternal behavior can pline, and self-control. But they soon found their way buffer the young animal’s hippocampus against the onto the same dispiriting life trajectories as their par- effects of stress. This is consistent with the hypoth- ents, with limited skills, options, hope. As a mother, esis that the stressful environment of poverty affects I found it heartbreaking. As a scientist, I wanted to hippocampal development, with additional help or understand. hindrance from parenting. This led to a series of studies in which my col- My daughter is now 19, and the field of poverty laborators and I tried first to simply document the neuroscience is growing up too! Many research effects of childhood poverty in terms of cognitive groups are now studying SES and child development neuroscience’s description of the mind, and then to through the lens of neuroscience. Brain imaging by explain the effects of poverty in terms of more spe- our group and others shows structural and functional cific, mechanistic causes. With Kim Noble, then a differences in the brain. One recent study of hippo- graduate student in my lab, we assessed the func- campal volume in children found SES differences and tioning of five different neurocognitive systems in also found that these differences were attributable to kindergarteners of low and middle SES. We found stress and maternal behavior, consistent with our ear- the most pronounced effects in language and execu- lier hypothesis. Fortunately, although the developing tive function systems. These results were replicated brain is vulnerable to the effects of poverty, neurosci- and expanded upon in additional studies with Noble ence tells us that the brain can change in response to and with Hallam Hurt, a pediatrician collaborator. In positive environments at any age. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 44 CHAPTER 2 Cognitive Neuroscience Cerebral Cortex and Localization of Function The cerebral cortex plays an extremely important role in human cognition. It enables us to think. Because of it, we can plan, coordinate thoughts and actions, perceive visual and sound patterns, and use language. Without it, we would not be human. The cerebral cortex forms a 1- to 3-millimeter layer that wraps the surface of the brain somewhat like the bark of a tree wraps around the trunk. In human beings, the many convolutions, or creases, of the cerebral cortex include three elements. Sulci (singular: sulcus) are small grooves. Fissures are large grooves. And gyri (singular: gyrus) are bulges between adja- cent sulci or fissures. These folds greatly increase the surface area of the cortex. If the wrinkly human cortex were smoothed out, it would take up about 2 square feet. The cortex makes up 80% of the human brain (Kolb & Whishaw, 1990). The volume of the human skull has more than doubled over the past 2 million years, allowing for the expansion of the brain, and especially the cortex (Toro et al., 2008). The surface of the cerebral cortex is grayish (see also Figure 2.1). It is sometimes referred to as gray matter because it primarily includes the grayish neural-cell bodies that process the information that the brain receives and sends. In contrast, the underlying white mat- ter of the brain’s interior includes mostly white, myelinated axons. The cerebral cortex forms the outer layer of the two halves of the brain—the left and right cerebral hemispheres (Davidson & Hugdahl, 1995; Galaburda & Rosen, 2003; Gazzaniga & Hutsler, 1999; Levy, 2000). Although the two hemispheres appear to be similar, they function differently. The left cerebral hemisphere is specialized for some kinds of activity, whereas the right cerebral hemisphere is specialized for other kinds. For example, receptors in the skin on the right side of the body generally send informa- tion through the medulla to areas in the left hemisphere in the brain. The receptors on the left side generally transmit information to the right hemisphere. Similarly, the left hemisphere of the brain directs the motor responses on the right side of the body. The right hemisphere directs responses on the left side of the body. Not all information transmission is contralateral—from one side to another (con- tra-, “opposite”; lateral, “side”). Some ipsilateral transmission—on the same side— occurs as well. For example, odor information from the right nostril goes primarily to the right side of the brain. About half the information from the right eye goes to the right side of the brain; the other half goes to the left side of the brain. In addition to this general tendency for contralateral specialization, the hemispheres also communi- cate directly with one another. The corpus callosum is a dense aggregate of neural fibers connecting the two cerebral hemispheres (Witelson, Kigar, & Walter, 2003). It transmits information back and forth. Once information has reached one hemisphere, the corpus callosum transfers it to the other hemisphere. If the corpus callosum is cut, the two cere- bral hemispheres—the two halves of the brain—cannot communicate with each other (Glickstein & Berlucchi, 2008). Although some functioning, such as language, is highly lateralized, most functioning—even language—depends in large part on integration of the two hemispheres of the brain. See Lab14, Brain Asymmetry, in CogLab. Hemispheric Specialization How did psychologists find out that the two hemispheres have different responsibilities? The study of hemispheric specialization in the human brain can be traced back to Marc Dax, a country doctor in France. By 1836, Dax had treated more than 40 patients suffer- ing from aphasia—loss of speech—as a result of brain damage. Dax noticed a relation- ship between the loss of speech and the side of the brain in which damage had occurred. In studying his patients’ brains after death, Dax saw that in every case there had been damage to the left hemisphere of the brain. He was not able to find even one case of speech loss resulting from damage to the right hemisphere only. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 45 In 1861, French scientist Paul Broca (1824–1880) claimed that an autopsy revealed that an aphasic stroke patient had a lesion in the left cerebral hemisphere of the brain. By 1864, Broca was convinced that the left hemisphere of the brain is critical in speech, a view that has held up over time. The specific part of the brain that Broca identified, now called Broca’s area, contributes to speech (Figure 2.4 ). Another important early researcher, German neurologist Carl Wernicke, studied lan- guage-deficient patients who could speak but whose speech made no sense. Like Broca, he traced language ability to the left hemisphere. He studied a different precise location, now known as Wernicke’s area, which contributes to language comprehension (Figure 2.4). Karl Spencer Lashley, often described as the father of neuropsychology, started study- ing localization in 1915. He found that implantations of crudely built electrodes in appar- ently identical locations in the brain yielded different results. Different locations sometimes paradoxically yielded the same results (e.g., see Lashley, 1950). Subsequent researchers, using more sophisticated electrodes and measurement procedures, have found that spe- cific locations do correlate with specific motor responses across many test sessions. Appar- ently, Lashley’s research was limited by the technology available to him at the time. Sensory cortex Motor cortex Association Association cortex cortex Auditory cortex Broca’s area (speech) Visual cortex Wernicke’s area (understanding language) Figure 2.4 Functional Areas of the Cortex. Strangely, although people with lesions in Broca’s area cannot speak fluently, they can use their voices to sing or shout. Source: Adapted from Psychology: In Search of the Human Mind by Robert J. Sternberg, 2000 by Harcourt Brace & Company. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 46 CHAPTER 2 Cognitive Neuroscience Despite the valuable early contributions by Broca, Wernicke, and others, the individual most responsible for modern theory and research on hemispheric specialization was Nobel Prize–win- ning psychologist Roger Sperry. Sperry (1964) argued that each hemisphere behaves in many respects like a separate brain. In a classic experiment that supports this contention, Sperry and his colleagues severed the corpus callosum connecting the two hemispheres of a cat’s brain. They then proved that information presented visually to one cerebral hemisphere of the cat was not recogniz- able to the other hemisphere. Similar work on monkeys indicated the same discrete performance of each hemisphere (Sperry, 1964). Some of the most interesting information about how the human brain works, and especially about the respective roles of the hemispheres, has emerged from studies of humans with epilepsy in whom the corpus callosum has been severed. Surgically severing this neurological bridge pre- vents epileptic seizures from spreading from one hemisphere to another. This procedure thereby drastically reduces the severity of the seizures. However, this procedure also results in a loss of com- munication between the two hemispheres. It is as if the person has two separate specialized brains processing different information and performing separate functions. Patients who have undergone an operation severing the corpus callosum are called split-brain patients. Split-brain research reveals fascinating possibilities regarding the ways we think. Many in the field have argued that language is localized in the left hemisphere. Spatial visualization ability (i.e., the ability to mentally manipulate two- or three-dimensional objects) appears to be largely local- ized in the right hemisphere (Farah, 1988a, 1988b; Gazzaniga, 1985). Spatial-orientation tasks also seem to be localized in the right hemisphere (Vogel, Bowers, & Vogel, 2003). It appears that roughly 90% of the adult population has language functions that are predominantly localized within the left hemisphere. There are indications, however, suggesting that the lateralization of left-handers dif- fers from that of right-handers, and that for females, the lateralization may not be as pronounced as for males (Vogel, Bowers, & Vogel, 2003). More than 95% of right-handers and about 70% of left-handers have left-hemisphere dominance for language. In people who lack left-hemisphere processing, language development in the right hemisphere retains phonemic and semantic abilities, but it is deficient in syntactic competence (Gazzaniga & Hutsler, 1999). The left hemisphere is important not only in language but also in movement. People with apraxia—disorders of skilled movements—often have had damage to the left hemisphere. These people have lost the ability to carry out familiar purposeful movements such as forming letters when writing by hand (Gazzaniga & Hutsler, 1999; Heilman, Coenen, & Kluger, 2008). Another role of the left hemisphere is to examine past experiences to find patterns. Finding patterns is an important step in the generation of hypotheses (Wolford, Miller, & Gazzaniga, 2000). The right hemisphere is largely “mute” (Levy, 2000). It has little grammatical or phonetic under- standing. But it does have good semantic knowledge. It also is involved in practical language use. Peo- ple with right-hemisphere damage tend to have deficits in following conversations or stories. They also have difficulties in making inferences from context and in understanding metaphorical or humorous speech (Levy, 2000). The right hemisphere also plays a primary role in self-recognition. In particular, the right hemisphere seems to be responsible for identifying one’s own face (Platek et al., 2004). In studies of split-brain patients, the patient is presented with a composite photograph that shows a face that is made up of the left and right side of the faces of two different persons (Figure 2.5 ). They are typically unaware that they saw conflicting information in the two halves of the picture. When asked to give an answer about what they saw in words, they report that they saw the image in the right half of the picture. When they are asked to use the fingers of the left hand (which contralat- erally sends and receives information to and from the right hemisphere) to point to what they saw, participants choose the image from the left half of the picture. Recall the contralateral association between hemisphere and side of the body. Given this association, it seems that the left hemisphere is controlling their verbal processing (speaking) of visual information. The right hemisphere appears to control spatial processing (pointing) of visual information. Thus, the task that the participants are asked to perform is crucial in determining what image the participant thinks was shown. Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Cognitive Neuroscience CHAPTER 2 47 Gazzaniga (Gazzaniga & LeDoux, 1978) does not believe that the two hemispheres function completely independently but rather that they serve complementary roles. For instance, there is no language processing in the right hemisphere (except in rare cases of early brain damage to the left hemisphere). Rather, only visuospatial processing occurs in the right hemisphere. As an example, Gazzaniga has found that before split-brain sur- gery, people can draw three-dimensional representations of cubes with each hand (Gaz- zaniga & LeDoux, 1978). After surgery, however, they can draw a reasonable-looking cube only with the left hand. In each patient, the right hand draws pictures unrecogniz- able either as cubes or as three-dimensional objects. This finding is important because of the contralateral association between each side of the body and the opposite hemisphere Figure 2.5 A Study with Split-Brain Patients. In one study, the participant is asked to focus his or her gaze on the center of the screen. Then a chimeric face (a face showing the left side of the face of one person and the right side of another) is flashed on the screen. The participant then is asked to identify what (a) he or she saw, either by speaking or by pointing to one of several normal (not chimeric) faces. AP Images/Dima Gavrysh DFree/Shutterstock.com iStockphoto.com/EdStock DFree/Shutterstock.com Madonna: Dino de Laurentiis/The Kobal Collection/The Picture Desk; Oprah Winfrey: Dima Gavrysh/