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Chapter 13

CHAPTER 13 NOTES - Evolutionary Psych

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York University
PSYC 3420
Irwin Silverman

CHAPTER 13: TOWARD A UNIFIED EVOLUTIONARY PSYCHOLOGY • Psychology: a scientific discipline devoted to studying humans • Cognitive psychologists: study how the mind processes information o Have documented an array of cognitive biases and heuristics, that suggests that the human mind fails to function according to formal rules of logic • Social psychologists: study interpersonal interactions and relationships o Discovered phenomena such as: social loafing, obeying authority figures, etc. • Developmental psychologists: study how humans change psychologically throughout their life o Discovered that children develop an understanding at age 3 that other people have desires, don’t understand until age 4 that people have beliefs, and don’t understand puberty until that people have sexual desires • Personality psychologists: study the differences between people (some study human nature) o Discovered: some people are consistently more Machiavellian or manipulative than others • Cultural psychologists: study the differences between individualists and collectivists cultures • Clinical psychologists: study way the mind malfunctions o Discovered: twice as many women as men suffer from depression schizophrenia shows substantial heritability and is nearly impossible to cure, common phobias can be cured through systematic desensitization treatment EVOLUTIONARY COGNITIVE PSYCHOLOGY • Psychological mechanisms entail information-processing devises that are tailored to solving adaptive problems • Traditional cognitive psychology is anchored by several core assumptions that evolutionary psychology challenges: 1. Mainstream cognitive psychologists tend to assume that cognitive architecture is general-purpose and content-free • These general purpose mechanisms include the abilities to reason, learn, imitate, calculate means-ends relationships, compute similarity, form concepts, and remember things • Cognitive psychologists tend to select stimuli on the basis of ease of presentation and experimental manipulability • There are at least two major problems with the assumption of general- purpose processing mechanisms: i. What constitutes a successful adaptive solution differs from domain to domain ii. The number of possible behaviours generated by unconstrained general mechanisms approaches infinity, so the organism would have no way of distinguishing successful adaptive solutions form the blizzard of unsuccessful ones 2. Functional agnosticism: the view that information-processing mechanisms can be studied without the adaptive problems they were designed to solve EVOLUTION CHAPTER 13 page 1 • Evolutionary psychology in contrast, infuses the study of human problems they were designed to solve • Evolutionary psychologists replace the core assumptions of mainstream cognitive psychology - general-purpose and content-free mechanisms along with functional agnosticism - with a different set of assumptions that permits integration with the rest of life science: 1. The human mind consists of a set of evolved information-processing mechanisms embedded in the human nervous system 2. These mechanisms and the developmental programs that produce them are adaptations produced by natural selection over evolutionary time in ancestral environments 3. Many of these mechanisms are functionally specialized to produce behaviours that solves particular adaptive problems, such as mate selection, language acquisition, and cooperation 4. To be functionally specialized, many of these mechanisms must be richly structured in content-specific ways • Computational theory: specifies what the problem is and why there is a device to solve it - it specifies the function of an information processing device; and is based on the following: 1. Information processing devices are designed to solve problems 2. They solve problems by virtue of their structure 3. To explain the structure of device, you need to know: a. What problem it was designed to solve b. Why it was designed to solve that problem • By itself, computational theory is not enough to establish precisely how a mechanism goes about actually solving an adaptive problem because any particular adaptive problem will have many potential solutions ATTENTION AND MEMORY • Attention is an inherently limited capacity • Human attention and memory are extremely selective, designed to notice, store, and retrieve information that has the most importance for solving adaptive problems • The study of human memory is also being illuminated by posing questions about evolved functions • James Nairne hypothesized that evolved memory systems should be at least somewhat domain specific, sensitive to certain kinds of content or information o Human memory should be especially sensitive to content and relevant to evolutionary fitness, such as survival, and reproduction • Using a standard memory paradigm involving a scenario priming task and a surprise recall task, they found that words previously rated for survival-relevance in scenarios were subsequently remembered at significantly higher rates than those rated for relevance in a variety of control scenario conditions • Rating the item's relevance in the survival scenario produced better recall performance than any other well-known memory-enhancing technique • They conclude that survival processing is one of the best encoding procedures yet identified in human memory research EVOLUTION CHAPTER 13 page 2 • Another study had participants who were in committed romantic relationships come into the lab for one session, during which they were asked to imagine encountering cues to their partner's infidelity • Some cues were more diagnostic of sexual infidelity and some cues were more diagnostic of emotional infidelity • A week later, participants were given a surprise memory recall test • Women more than men remembered cues to emotional infidelity, whereas men more than women remembered cues to sexual infidelity • What we remember corresponds closely to the adaptive problems we need to solve; in this case: the sex-linked adaptive problems of sexual vs. emotional infidelity PROBLEM SOLVING: HEURISTICS, BIASES, AND JUDGEMENT UNDER UNCERTAINTY • Errors and biases to which humans are predisposed: 1. Base-rate fallacy: people tend to ignore base-rate information when presented with compelling in dividing information • It refers to the overall proportion of something in a sample or population 2. The conjunction fallacy: when people assume that specific conditions are more probable than a single general one • Tooby and Cosmides argue that an evolutionary perspective present something of a paradox when contrasted with the view of humans as riddled with cognitive biases • Humans routinely solve complex, natural tasks, many of which have defied attempts to be modeled in artificial intelligence systems • Tooby and Cosmides argue for an evolutionary theory of cognitive mechanisms that are called ecological rationality • Statistical regularities are called ecological structure • Ecological rationality consists of evolved mechanisms containing design features that utilize ecological structure to facilitate adaptive problem solving • When there is a mismatch between the problem presented and the problem mechanism was designed to solve, errors will result • Theories of formal logic that are content independent are exceptionally poor at solving real adaptive problems • Human adaptive problem solving always depend on three ingredients: 1. The specific goal being sought 2. The materials at hand 3. The context in which the problem is embedded • The human mind may have been well designed to record the frequency of events • If some mechanisms of the mind are designed to record event frequencies rather than single-event probabilities then experiments that require subjects to calculate probabilities from single events may be presenting artificial and evolutionary novel stimuli • Cosmides and Tooby advance the frequency hypothesis: the proposition that some human reasoning and mechanisms are designed to take as input frequency information and produce as output frequency information • Advantages of frequency representations: EVOLUTION CHAPTER 13 page 3 1. They allow a person to preserve the number of events on which the judgement was based 2. They allow a person to update his/her database when new events and information are encountered 3. They allow a person to construct new reference classes after the events have been encountered and remembered, and to recognize the database as needed •EXAMPLE: THE MEDICAL DIAGNOSIS PROBLEM (page 398) 1. When the information is presented in a format using frequencies, performance improves dramatically 2. Performance improves even more when the information is presented pictorially in visual format 3. Presenting the information verbally allows 3/4 of the subjects to get it right, but adding a visual frequentist representation allows almost all subjects to get it right • These results suggests that people do not ignore base-rate information in making judgements, as long as the base-rate information is presented in a manner that maps more closely onto the sorts of inputs that humans would have been likely to process in ancestral times •It does not mean that the human mind lacks cognitive biases; rather many of the cognitive heuristics it contains are "adaptively biased" •Thus, the "descent illusion" and "auditory looming bias" are perceptual biases that problems of survival •Women's "commitment skepticism bias" is designed to solve the problem of mating •Humans are "adaptively rational" THE EVOLUTION OF LANGUAGE IS LANGUAGE AN ADAPTATION OR A BY-PRODUCT •Two sides to this debate: 1. One side argue that language is not an adaptation at all, but rather a by-product or side effect of the tremendous growth of the brain • Chomsky and Gould acknowledge that the growth of the human brain itself resulted from natural selection • After the brain attained its current size and complexity, language simply emerged spontaneously as one of the many side effects • Ex. Language is to the large human brain as heat is to the reading lamp - an emergent product but not central to its function or purpose • A more recent of this view suggests that human language may have been guided by particular selection pressures, unique to our evolutionary past, or a by-product of other kinds of neural organizations 2. Steven Pinker proposes that language is an adaptation par excellence - product by natural selection for communication of information • The deep structure of grammar is too well designed for the function of communication for it to be merely an incidental by-product of big brains • It includes elements that are universal across all languages (ex. Nouns), and rules that govern the structure of phrases • Children become fluent speakers of complex grammatical sentences early in life, usually by age 3, without any formal teaching or instructions EVOLUTION CHAPTER 13 page 4 • Language is linked to specific regions of the brain - Wernicke's Area and Broca's Area - and damage to these regions results in language impairment • The vocal tract of humans seems specially designed for producing the multitudes of sounds needed for language • Auditory perception shows precise complementary specializations that allow us to decode the speech produced by other humans • When all these points are added up, Pinker proposes, they suggest that language is an adaptation • Language shows universal complexities of design for the communication of information and the only known explanation for the origins of complex organic structures is evolution by natural selection • Language is an "instinct" WHAT ADAPTIVE PROBLEMS DID LANGUAGE EVOLVE TO SOLVE? • The dominant theory of the function of language is that it evolved to facilitate communication - the exchange of information between individuals • Three theories of the function of language have been proposed (all involving social functions): 1. Social gossip hypothesis: language evolved to facilitate bonding among large groups of humans • Dunbar argues that language is a form of "social grooming" - 2. Social contract hypothesis: problems of mating became more problematic when large game hunting emerged; language evolved to facilitate explicit marriage contracts • This hypothesis encounters difficulties: it fails to explain how cohesive large groups form to being with, why other species appear to solve these mating problems without resorting to language, and why marriage contracts so frequently fail 3. Scheherazade hypothesis: after the main character in The Arabian Nights - to prevent being killed, Scheherazade regaled the king with such entertaining tales that each morning he decided against killing her • The large brain is essentially like the peacock's tail - evolved to signal superior fitness to potential mates • By dazzling potential mates with humor, wit, exotic tales, and word magic, those with superior language skills had a mating advantage over their mumbling competitors THE EVOLUTION OF EXTRAORDINARY HUMAN INTELLIGENCE • Although the human brain makes up only 2-3% of the average human's body weight, it consumes about 20-25% of the body's calories • Human's brains are larger, relative to body size, compared to any other primate • Over the past several millions years, the human brain has tripled in size • Ecological dominance/social competition (EDSC) hypothesis: human ancestors were able to subdue many of the traditional "hostile forces of nature" that previously impeded survival EVOLUTION CHAPTER 13 page 5 o The hostile forces include the "Four Horsemen of Apocalypse", which are starvation, warfare, pestilence, and extreme weather o According to this hypothesis, human dominance over the ecology opened the door to a new set of selective forces - competition from other humans • The size of ancestral human groups, in the range of 50-150 individuals, adds to the complexities of social adaptive problems, selecting for larger brains and greater levels of social intelligence • These new forms of intelligence are hypothesized to include consciousness, language, self-awareness, and theory of mind • They also included "scenario building", which allowed people "to construct and rehearse responses to changing situations" • One empirical prediction from the EDSC hypothesis is that a population density increases, selection pressure for greater intelligence should increase due to the more taxing demands of social competition • Bailey and Geary gathered data from 175 hominid crania dating from 10,000 to 1.9 million years ago • Using proxies for population density for the locations of the skulls, they found that indeed cranial capacity was higher in locations of higher population density • They concluded that although multiple pressures drove the evolution of human intelligence, "the core selective force was social competition" • Linda Gottfredson challenges the EDSC hypothesis for the evolution of human intelligence • She argues that general intelligence (as measured by IQ tests) is not highly correlated with "social intelligence", as predicted by the EDSC hypothesis • The technological feats of humans have raised the average of survival rates of humans have not eliminated individual differences in survival - differences that would have selected for higher levels of general intelligence • Therefore, individual differences in survival, even today, are linked with individual differences in intelligence • The very technologies that humans have invented to aid in their survival (fire, tools, weapons, canoes) have created novel hazards for humans • Among the !Kung of Botswana, for example "the most serious cause of hunting accidents, in the sense of injuries leading to death, is not the animals themselves, but the weapons that the !Kung use to kill those animals • Gottfredson's deadly innovations hypothesis proposes that human innovation has created and even amplified the relative risk of injury and premature death, creating selection pressure for the evolution of general intelligence • According to this hypothesis, several forces occurring over the past 1/2 million years would have widened the survival difference between individuals of higher and lower general intelligence 1. The first is double-jeopardy: not only do the less intelligent become injured and die at higher rates, their children also suffer greater mortality as a consequence of the parents not being able to protect and provide for them EVOLUTION CHAPTER 13 page 6 2. The second is spiraling complexity: as technologies become increasingly complex, they amplify the importance of general intelligence for avoiding the new hazards they bring 3. The third is migration ratchet: as humans migrated out of Africa and into the new and previously unexploited territories of Europe, Asia, The Americas, even the Arctic, these new environments created pressure for even more innovative technologies to harness them, creating even more novel hazards • Empirical support for the deadly innovations hypothesis comes from several sources: 1. One study found that each additional IQ point, such as 107 vs. 106, was linked with a 1% reduction in the relative risk of death • This means that having an IQ 15 points above average would decrease mortality risk by 15% 2. IQ is also linked with sublethal injuries, which themselves hurt an individual's inclusive fitness • In the modern world, those with lower IQs are more likely to drown, get into car/bike accidents, inured through explosions, falling objects, and knives, and even be hit by lightning EVOLUTIONARY SOCIAL PSYCHOLOGY • Many of the most important adaptive problems humans have faced over the past several million years are inherently social in nature: negotiating social hierarchies, forming long- term social exchange relationships, using language to communicate and influence others, forming short-term and long-term mateships, managing social reputations admits a landscape of shifting allies and rivals, and dealing with kin of varying and uncertain degrees of genetic relatedness • Much of evolutionary psychology, therefore, will be evolutionary social psychology • Psychology of relationships should form the core of the field of social psychology • This focus on relationships is in sharp contrast to much mainstream social psychology, which tends to be a "phenomenon" • Some interesting, counterintuitive, or anomalous observation is noticed and empirically documented, examples are: 1. The correspondence bias, the tendency to explain a person's behaviour by invoking enduring dispositions, even when it can be shown that situational causes are responsible 2. The social loafing effect, the tendency for individuals to perform less work toward a joint outcome as a group size increases 3. Self-handicapping, the tendency to present publicly a purported weakness about oneself to provide an excuse in the event one fails at a task 4. The self-serving bias, the tendency to make attributions that make oneself look better than others in the group 5. The confirmation bias, the tendency to selectively seek out information that affirms an already-held hypothesis CAPITALIZING ON EVOLUTIONARY THEORIES ABOUT SOCIAL PHENOMENA EVOLUTION CHAPTER 13 page 7 Important evolutionary theories for social psychology: 1. Inclusive fitness theory o A direct implication of inclusive fitness theory is that altruistic acts should be heavily directed toward other organisms that a. Are likely to have copies of the helper's genes and, b. Have the ability to convert such help into increased survival reproduction o This theory has profound consequences for the social psychology of the family, helping, coalitions, and even aggression 2. Sexual selection theory o The theory that evolution can occur through mating advantage accrued through: a. Besting intrasexual competitors, and b. Being preferentially choses as a mate by members of the opposite sex o This theory is invaluable to discover key psychological mechanisms in same-sex competition, homicide and other forms of violence, risk taking, mate choice, conflict between sexes, sex differences in status striving, and even sex differences in the risk of dying 2. Parental investment theory o The sex that invests more in an offspring is predicted to be more choosy in mate selection o The sex that invests less in an offspring is predicted to be less choosy in mate selection and more competitive with its own sex for sexual access to high-investing sex o This theory has led to many important discoveries about strategies of human mating 3. Reciprocal altruism theory o Offers an evolutionary explanations for many social phenomena such as, friendship, cooperation, helping, altruism, and social exchange 4. Parent-offspring conflict theory o Conflicts are common in most families o It supplies an explanation for sibling rivalry, child abuse in stepfamilies o It also predicts conflict between children and their parents over activities such as extramarital involvement, which may be beneficial to the parent but costly for the child 5. Sexual conflict theory o Provides a powerful guide to the ways in which men and women get into conflict o Patterns of male and female deception on the mating market, sexual aggression, women's defenses against sexual aggression and jealous conflict within mating relationship THE EVOLUTION OF MORAL EMOTIONS • Human intuitions dovetail with evolutionary theory in telling us that our standards of morality are likely to be biased in favor of genetic relatives •What causes us to have moral views? Historical approaches to morality have been dominated by "rationalist" theories, whereby people arrive at a moral judgement through moral reasoning •By logic and rationality, we presumed to weigh the issues of right and wrong, and arrive at the morally correct answer •John Haidt challenged this view, arguing instead that humans have evolved moral emotions that produce quick automatic evaluations EVOLUTION CHAPTER 13 page 8 • Only subsequently, when we are forced to explain or rationalize our moral stances, do we grasp for the straws of reasoning that we hope will support a judgement we've already come to • Haidt found reactions from participants of a study that, when asked for reasons of why participants think a situation is wrong, they have difficulty explaining • A plausible explanation is that humans have evolved moral emotions • The repulsion of incest evolved to prevent inbreeding and is invoked in reaction to sex between Julie and Mark (page 407) • Similar functional logic can be applied to other moral emotions: • Anger toward cheaters likely evolved to punish those who violate social contracts • In a study, participants rated variety of different endings to Hollywood film clips that portrayed a serious injustice • Participants were displaced by endings in which the victim of an injustice accepted the loss, forgave the transgressor, and found growth and fulfillment • They were most satisfied with endings in which the perpetrators of the injustice suffered greatly, knew that the suffering was retribution for the transgression, and experienced public humiliation in the process • In short, the moral outrage that people experience at cheating and violations of social contracts might have evolved to serve a policing function, holding others to their commitments and obligations • Embarrassment might have evolved to promote appeasement and submission • Both shame and embarrassment motivate the desire to high and withdraw, reducing one's social presence • Displays of shame might minimize attack or punishment from dominant others, lowering costs to the violator of the moral code • Guilt is often regarded as a protypical emotion • Whereas shame is linked to hierarchical interactions, guilt stems from violations of communal relationships • It is likely to have evolved to signal to the harmed party that you know that you have inflicted a harm and it also signals that you are motivated to repair the harm • Evolutionary hypotheses have also been advanced for other moral emotions such as contempt, sympathy, gratitude • Two other examples highlight the centrality of morality to social adaptive problems 1. One centers on the in-group distinction vs. out-group distinction, which often provides boundaries for determining who deserves moral treatment and who does not • Navarrete has found that conditioned fear responses to in-group members can be easily extinguished, but fear toward out-group members is stubbornly difficult to extinguish • It is fear of male out-group members that proves especially difficult to extinguish • Prejudice toward male out-group may have helped human ancestors to solve adaptive problems of defense against physical aggression for men, and defense against sexual coercion for women EVOLUTION CHAPTER 13 page 9 2. Sexual selection provides another link between morality and social adaptive problems • Miller proposes that many things we consider to be morally virtuous are precisely the qualities we find attractive in a mate • Virtues such as kindness, fidelity, sacrifice for others, and magnanimity are desirable in mates because they advertise good parenting and good partner qualities, and possibly good genetic qualities, and so may have been sexually selected over many thousands of generations of human evolution •Moral emotions might serve as "commitment devices" that promote prosaically deeds, reparation of harm, and punishment of cheaters, all while signalling to others that one is a good coalitional ally and can be relied on in the future •The adaptive problems they solve can be grouped into three major classes: 1. Respect for authority - restraining one's selfish urges by deferring to those in a dominant position and obeying laws, rules, and commandments from higher authority 2. A thirst for justice - the adaptive value of cooperation and reciprocity, including the punishment of cheaters to avoid the collapse of beneficial mutualism 3. Evolution of care - the adaptive value of devotion, sympathy, giving toward allies, mates, and kin THE RETURN OF GROUP SELECTION AS MULTILEVEL SELECTION THEORY •Group selection - the idea that there are group-level adaptations that evolved through the differential reproduction and extinction of groups •Williams showed that group selection is theoretically possible and may indeed have occurred for some species such as honeybees • Williams envisioned that group selection is a "weak force" •Conclusion was that the conditions that make group selection likely, such as: 1. A high degree of "shared fate" of members within the group 2. Low levels of reproductive competition within the group 3. Recurrent patterns of differential reproduction and extinction of groups Are rarely seen in nature, and unlikely to have been a strong force for most species •Wilson and Sober have argued that group selection is far more viable than most biologists had concluded •The argument centers on the issue of whether groups can have functional organization in the same way that individuals have functional organization •Individuals can be seen as "vehicles" of selection, so groups too can be seen as "vehicles" of selection •Multilevel selection theory - selection can operate on many levels, including individuals, groups within species, and even larger entities such as multispecies ecosystems •Many biologists and evolutionary psychologists argue that the conditions required to make group selection a powerful force are rarely met, especially with humans EVOLUTIONARY DEVELOPMENTAL PSYCHOLOGY EVOLUTION CHAPTER 13 page 10 •developmental psychology cuts across the other traditional branches of psychology and is defined by its temporal perspective rather than by its psychological content •because few psychological mechanisms emerge at birth fully developed, a developmental perspective will necessarily be an essential part of the proper description and understanding of nearly every psychological mechanism •evolutionary developmental psychologists tend to tress the important of the following conceptual issues: 1. natural selection occurs throughout the life span, but selection tends to be especially strong early in life-if an individual fails it survive infancy and childhood, it can't reproduce 2. adaptations in infancy and childhood solve adaptive problems e.g. The suckling reflex of the infant functions to obtain breast milk, or prepare the individual for a problem it will face later 3. the extended childhood characteristics of humans prepare them for the complexities of social living later in life 4. children have conditional adaptations, which allow them to respond flexibly to features of the childhood environment with strategies that are effective in coping with environments that those features statistically predicting gene- environment interactions occur throughout development •one key insight currently missing from mainstream developmental psychology is this: human beings face predictably different adaptive problems at various points in their lives •e.g. Infants face the problem of survival but not mating •problems of mating are faced predictably before problems of parenting etc Theory of Mind Mechani
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