Samstag, 26. November 2016
Richard D. Alexander (2005)
"Ronald A. Fisher (1930) used the adjective runaway to apply to a hypothetical selective process that he assigned to sexual selection (see also Trivers 1972; Miller 2000). I suggest that sexual selection and reciprocity selection are special forms of the broader concept of social selection. Social selection is a consequence of competition among individuals for rewards arising out of various kinds of social or mutualistic beneficence.
Fisher’s runaway sexual selection has two special features. First is the tendency of the choosing parties to begin favoring individuals with traits that are extreme on some axis of desirability, rather than favoring some particular condition (other than extremeness) of the individuals to be chosen. This form of choosing can only occur in an organism that is able to compare an array of individuals and identify desirable extremes (e.g., Alexander, Marshall, and Cooley 1997). It can evolve to become the standard method of choice only if selection continues for a long time in one direction and the best choices continue to be beyond the previous expressions of the trait. Thus, if females that choose extreme males outreproduce those that do not, the choosing of extremes will spread. So will extremeness in males; otherwise the females choosing them would not gain. Spreading or fixing the choosing of extremes will inject a certain degree of inertia into the process. For this reason, once an “extreme-choosing” tendency is in place, extremes in the traits of the chosen individuals can pass beyond the form in which they are adaptive in any other sense and indeed can become disadvantageous in other contexts. Some such conflict actually exists among all the compromises of selection on different traits of the organism because the effect of selection can only be enhancement of the reproductive integrity of the organism as a whole rather than the state of any of its individual traits. When selection is social, however—when it is a matter of individuals choosing other individuals in a mutualistic or reciprocal social interaction rather than, say, competition to detect or capture food, or to escape enemies more effectively—overshoots in adaptiveness in other respects, because of choosing extremeness, will be more prominent.
The second special feature of Fisher’s runaway sexual selection is the feedback resulting from the genetic partnership between males and females in jointly produced offspring. Trivers (1972, 166) described it as follows:
>[I]f there is a tendency for females to sample the male distribution and to prefer one extreme (for example, the more brightly colored males), then selection will move the male distribution toward the favoured extreme. After a one generation lag, the distribution of female preferences will also move toward a greater percentage of females with extreme desires, because the granddaughters of females preferring the favoured extreme will be more numerous than the granddaughters of females favoring other male attributes. Until countervailing selection intervenes, this female preference will, as first pointed out by Fisher (1958), move both male attributes and female preferences with increasing rapidity in the same direction.<
We can note, first, that some aspects of human evolution that intrigue us, such as brain functions that result in cleverness in social interactions, including scenario building and testing the social future by weighing alternatives internally, could have evolved partly through sexual selection. In view of the tendency of the human brain to become larger across history, and of human behavior to become more complex—and seemingly ever more rapidly after these features had exceeded their counterparts in other species—we might be concerned to examine the likelihood that runaway sexual selection is involved. A related question is whether some or all features of runaway selection can also occur in nonsexual social interactions such as the high-risk forms of social reciprocity that are prominent only in the human species.
At first one may imagine that there are no parallels in social selection allowing it to become runaway. But the way an individual gains by selecting its social partners parallels the ways an individual can gain from cooperative interactions with a mate and from a mate’s parental care. In both cases there is likely to be genetic change in both the ability to choose good partners and the background of the favored phenotypic attributes because a mutually beneficial interaction can be maintained only if, on average, both interactants gain.
Sexual selection is a distinctive kind of runaway selection because joint production of offspring by the interacting pair causes the process to accelerate (see above Trivers quote). The defining feature of runaway selection is not acceleration, however, but the tendency of the process to go significantly beyond adaptiveness in all contexts except within the particular selective race—much further beyond adaptiveness in other contexts than is ordinarily the case in the myriad compromises among the conflicting adaptive traits that create and maintain the unified organism.
This aspect of runaway selection may hold for reciprocity selection, in which, unlike in sexual selection, both parties can carry tendencies not only to choose extremes but also to display extremes. In social selection, again unlike in sexual selection (except in simultaneous hermaphrodites), an individual can play both roles, of chooser and chosen, with respect to the same traits, and alternations of roles can occur during extended interactions between particular partners. To the extent that social success in ecologically dominant humans (see earlier) becomes the central determinant of reproductive success, runaway reciprocity selection may be a more viable possibility than Fisherian runaway sexual selection.
Fisherian runaway sexual selection presumably begins with a likelihood of heritability (i.e., genetic variability) in both variations in choices and variations in chosen traits. It is easy to see that in this circumstance such competitions, or races, will lead to genetic changes, at first changing both the ability and tendency to choose extremes and the nature of the extremes available for choice. Continuing mutations and genetic recombination (outbreeding among temporarily isolated groups) will tend to offer the choosing parties increasingly extreme possible choices, though to a reduced degree as selection continues to remove heritable variations in trait expressions and the trait becomes sufficiently maladaptive in contexts other than sexual selection. From earlier arguments it is not easy to understand the extent to which relevant heritability is likely to disappear, or even become trivial.
Diminution (or disappearance) of heritability in variations will not necessarily change the tendency to choose extremes: in effect, if an ability and tendency to choose extremes in any of a variety of social races (at least in humans) could become genetically fixed in the population (including the ability and tendency to learn from others, or from observation, the values of such choosing), it could still offer advantages to the chooser of extremes (without evolutionary change in the trait per se) because of the usefulness of even nonheritable trait variations chosen in a social partner. Of course, there may be further evolutionary improvements in the ability to identify and use extreme traits even after all choosers are already choosing extremes.
On the other hand, heritable variations in what is chosen will result in a continued march toward greater extremes because this relative quality will not be fixed in the way the ability to identify and favor extremes can be fixed; extremes can be identified only by comparing whatever is available. In Fisher’s version of runaway selection, extremes win reproductively at first because they are ecologically superior, meaning functionally superior outside the choice situation itself. Later they continue to win because they are sexually (or, here, socially) superior, even though, as a result of the progress of selection involving choice of extremes, they may have be come so extreme as to be otherwise functionally (ecologically) inferior. Here, “sexually or socially superior” means that the choosing parties will have acquired a genetic composition that will cause them to choose the extreme, the resulting choice of the extreme individuals itself causing the chosen individuals to outreproduce.
Extremes, however, will be chosen whether or not, as extremes, they represent heritable variants. If extreme social performances yield special social opportunities to those displaying them (e.g., via their reputations as achievers or winners), then regardless of the basis for the superior performances (i.e., genetic variant or not), winning performances can yield benefits to the kin or other social associates of the individual with the extreme traits. Thus merely joining social competitions or races can pay, though only heritable variations, including the (variant) ability to choose the best from among multiple available races that might be entered, will yield evolutionary change. Heritable variations in the ability to choose appropriate races—including not only those generally likely to be profitable but those in which the choosing individual, because of his or her special traits, has a special likelihood of competing successfully—may be all that is needed to drive runaway reciprocity selection. The more different ways that success can be achieved through reciprocity competition, the more robust will be this type of social selection. This is a kind of selection that will yield at least part of the human type of social intelligence, perceptiveness, and perseverance. As we all know, status (or “reputation”) can exist independent of the adoption of a particular extreme in behavior, so the importance of any behavioral extreme in changing some aspect of culture can also depend on whether a prestigious person adopts, favors, or approves of it.
Since Fisherian runaway sexual selection in nonhuman organisms has remained controversial (or theoretical), but social parallels to it may be robust in human society, one may wonder if Fisher actually derived his idea from observing human social situations rather than from thinking about sexual selection in the birds he ultimately used as his examples. If so, it is likely not the only instance in which an evolutionist was inspired by human traits and tendencies to develop a general evolutionary explanation (e.g., Darwin’s observations on human selection of variations in domestic animals and the fact that Hamilton’s rule applies in its fullest extent as extensive differential nepotism across multiple levels of relatedness only in humans). This suggestion is ironic in another way, in view of the success with which academic biology departments have managed to exclude the human species from their consideration, leaving its analysis to the almost exclusively nonevolutionary approaches of social science and medical departments, and surely delaying acceptable explanations of the human species in evolutionary terms.
When extremes in particular directions are being chosen in social selection, new extremes never before experienced may be chosen above all other expressions of a trait. This behavior was originally referred to in European ethology as a “superoptimal stimulus” effect and is not specifically related to runaway selection. Whenever superoptimal stimulus effects can be identified, however, they suggest a history of choosing extremes, therefore the possibility of some form of runaway selection. If, for example, we perceive that during the past several centuries art— or even human sociality in general—has flourished and become an enormous and diverse enterprise compared to any “ancestral” condition it might have exhibited, we might suspect that this is evidence of a history of choosing extremes continually in short supply and consequently of some kind of runaway process in however artistry affects the securing of the resources of reproduction. Rather than evidence that evolution cannot be used to explain, say, the arts, explanations of recent flowerings of diversity and complexity in human enterprises can be sought by expanding our understanding of the various subprocesses of evolutionary selection. We should not be discouraged because the pathways to explanation become progressively more difficult and call for expansions of our understanding of the workings of the evolutionary process."
Freitag, 25. November 2016
Sonntag, 20. November 2016
Good at school = successful on the job? Explaining gender differences in scholastic and vocational success
Good at school = successful on the job? Explaining gender differences in scholastic and vocational success
Whereas girls and women outperform men in academic success, men outperform women on vocational success criteria. The present study sought to explain these opposing gender gaps by hypothesizing that, to some extent, different personality traits would promote success in the school and business environments. Using two samples comprised of academic track 11th graders (236) and adult professionals (124), we tested whether gender differences in personality partly explained the opposing gender gaps in academic and vocational success. Questionnaires measuring the Big Five, personality facets, intelligence, and GPA or vocational success criteria were used. Analyses revealed that intelligence, Conscientiousness, and Need for Achievement (AC) predicted both school and vocational success. Agreeableness and Need for Aggression (AG) (negatively) were associated with only academic success. Need for Affiliation (AF) and Need for Dominance (DO) predicted only professional success. Mediation analyses showed that AC, Openness to Experience, Agreeableness, and Conscientiousness (girls scored higher), and AG (girls scored lower) mediated gender differences in academic success. Gender differences in vocational success were mediated by DO (men scored higher), whereas AF (women scored higher) suppressed this relation. The results are discussed with respect to their theoretical and practical implications for understanding gender differences in school and at work.
Samstag, 19. November 2016
Freitag, 18. November 2016
Donnerstag, 17. November 2016
An Evolutionary Behaviorist Perspective on Orgasm
Diana S. Fleischman (2016)
Diana S. Fleischman (2016)
Evolutionary explanations for sexual behavior and orgasm most often posit facilitating reproduction as the primary function (i.e. greater rate of fertilization). Other reproductive benefits of sexual pleasure and orgasm such as improved bonding of parents have also been discussed but not thoroughly. Although sex is known to be highly reinforcing, behaviorist principles are rarely invoked alongside evolutionary psychology in order to account for human sexual and social behavior. In this paper, I will argue that intense sexual pleasure, especially orgasm, can be understood as a primary reinforcer shaped by evolution to reinforce behavior that facilitates reproductive success (i.e. conception through copulation). Next, I will describe an evolutionary account of social shaping. In particular, I will focus on how humans evolved to use orgasm and sexual arousal to shape the social behavior and emotional states of others through both classical and operant conditioning and through both reproductive and non-reproductive forms of sexual behavior. Finally, I will describe how orgasm is a signal of sensitivity to reinforcement that is itself reinforcing.
Orgasm, like other primary reinforcers, can make stimuli that are paired with it (e.g. a color, someone’s face, a specific smell) reinforcing.
Many scientists have been puzzled by women’s orgasmic frequency. Why don’t women consistently experience orgasm and, conversely, why do women have orgasms at all? The fact that women experience orgasm, at least some of the time, is one piece of evidence that orgasm is a primary reinforcer for some kinds of adaptive behavior.
Some (e.g. Prause, 2011) have speculated that it is precisely because orgasm is variable in women that it may be more reinforcing than it is for men; variable reinforcement has been found to be a greater driver of behavior that is resistant to extinction than consistent reinforcement (e.g. gambling on a slot machine is more resistant to extinction than pulling a lever with a consistent payout) (Pryor, 1999).
a woman who was easily orgasmic in a variety of conditions could be making a more costly error: being motivated to engage in behavior that is unlikely to result in the optimal reproductive outcome of conceiving with a genetically fit male who is free of disease (Miller, 2000).
If one considers attachment and affection to another person as a behavior that can be reinforced with orgasm, we might not expect consistent orgasmic and sexual pleasure. With animals, a behavior that is being successfully and consistently produced need not be reinforced consistently (e.g. a dog sitting), but behavior that is decreasing in frequency may need to be carefully shaped when any subtle cue of that behavior reappears. A waning behavior like affection or attachment may be more effectively strengthened by, for example, rewarding the desired cues with variable reinforcement (e.g. the slot machine example used earlier) (Pryor, 1999; Skinner, 1938).
Classical conditioning... is a process by which a neutral stimulus is paired with a primary reinforcer, like sexual pleasure or orgasm, which thereby makes the neutral stimulus in itself reinforcing. When two people engage in sexual behavior and have orgasms they are associating sexual pleasure with the characteristics of the other including proximity, smell, taste, and form; these all become secondary rewards/reinforcers. When two people have repeated erotic contact, they become classically conditioned to perceive one another as secondary reinforcers and can better shape one another toward their own strategic goals.
If one person in a dyad is associated with sexual pleasure, he or she can very easily engage in what is called ‘negative punishment’, withholding positive consequences for a behavior as a means of punishment and an adaptive tactic for extinguishing the behavior. Take, for example, ‘silent treatment’; If an individual values social interaction with a sexual partner, then taking away this reinforcer is a way of simultaneously punishing the behavior and no longer supplying positive reinforcement toward that behavior. Silent treatment will be much more painful if someone’s mere presence, eye contact, or voice is strongly secondarily reinforced by sexual pleasure. Furthermore, withdrawal of other stimuli often associated with orgasm like touch, eye contact, close proximity, and smell can be used more subtly (than silent treatment) to shape behavior both consciously and unconsciously.
A variety of tactics can be used to reinforce and punish others, especially if you are a secondary reinforcer to someone because of classical sexual conditioning. While this hasn’t been explored directly in the literature before, there is one paper that details possible ‘manipulation tactics’ that can be used between romantic partners (Buss, 1989): charm, silent treatment, coercion, reasoning, regression, and debasement. Each of these can be viewed from a social shaping perspective and most could be augmented with the association of sexual pleasure. The ‘charm’ tactic includes acts of love and affection, compliments, gifts, and promising a reciprocal favor in exchange for a behavior in the mate, other means of operantly and classically conditioning a partner than sexual behavior. We already discussed silent treatment above as an example of negative punishment.
Here, I want to stress that positive association between a behavior and a reinforcing outcome like sexual pleasure is unlikely to be overt and, in fact, may work better for strategic goals if the manipulation is covert or unconscious. Self-deception is likely at play here; people are rarely conscious of the ways they manipulate others, and consciously verbalizing how you are manipulating someone else through reinforcement, would likely be viewed as unethical or sociopathic. The tactics of manipulation people use both sexually and non-sexually very likely exceed those they can verbalize.
“Finding a compatible partner is an important part of mate choice. Members of different species do not make good mates. At the other pole, too much inbreeding can also reduce reproductive success. For many years it was supposed that, providing the two extremes were avoided, choice of mate was influenced by all the other factors that are known or assumed to be important … . However, even within the species excessive outbreeding may be costly for a variety of reasons (Bateson, 1980; Shields, 1983). This means that a balance between too much inbreeding and too much outbreeding may have to be struck more carefully than we previously supposed.”
Patrick Bateson (1983)
Natural Selection and the Analysis of Human Sociality
Richard D. Alexander (1977)
Incest avoidance may be regarded as an aspect of mate selection whereby, in general, close relatives of the opposite sex are unavailable or disfavored, while more distant relatives are favored or specified. Members of one's nuclear family are nearly always excluded as possible mates, and, in humans, certain close relatives, just outside the nuclear family, are nearly always either excluded or disfavored. Other relatives only a little more distant may be suitable, preferred, or prescribed mates. Distant relatives or nonrelatives may also be suitable, preferred, or prescribed mates. If fairly close relatives are preferred or prescribed, those more distant may as a result be more or less incidentally disfavored or excluded.
Genetic outbreeding does not necessarily imply that only the most distant possible relatives, or nonrelatives, are suitable marriage or sex partners. Restricting one's sexual or marriage partner to increasingly distant relatives involves increasing costs (Fig[. ...] 5). Thus, fewer individuals are available, greater distances may have to be traveled to locate them, and greater risks may be involved in securing them; deleterious partitioning of reproductive resources may also result from extreme outbreeding.
On the other hand, close inbreeding also has disadvantages. Thus, with outbreeding fewer deleterious recessive alleles are exposed, there is less chance of reproductive devaluing of relatives because of sexual competition (Hamilton, 1967), and reproductive resources may be advantageously partitioned, for example, to those levels at which they are likely to undergo maximal inflation of their value. The complex patterns of marriage regulations in human societies may thus be largely interpretable as aspects of nepotism in which genetic relatives are constrained against competition, for mates and other resources, which devalues collective effects on the inclusive fitnesses of parents and other relatives. This explanation of marriage patterns and rules focuses attention simultaneously on individual interests in obtaining mates and resources and collective or societal interest in minimizing competition deleterious to the inclusive fitnesses of individuals related to the competitors. Rules or practices resulting from such collective interests must often be compromises based on differences in interests, and differences in power or influence; frequently, the most satisfactory or practical compromise remains the same from one generation to the next. In this case a Darwinian model appears to draw together the phenomena of individual interests and cultural collectivity (including its continuity) in a fashion not previously accomplished with cultural or genetic models that ignored inclusive fitness (Alexander, ms.).
Since the costs of inbreeding diminish outward and the costs of outbreeding mount with its degree, the two lines necessarily cross at some point (Fig. 5). I suggest that in most human societies the lines cross somewhere near the level of first cousins, farther out when more distant cousins are readily available, and closer in when the particular heritable resources involved are deflated rather than inflated in value as a result of extensive partition. Thus, we may expect nomads with few heritable goods, such as Australian Aboriginals, to marry further out. Herdsmen and farmers, and members of titled or royal families, in particular, might tend to marry in. A very large number of factors may be involved in the exact degree of inbreeding and outbreeding, or in the selection of marriage partners at given levels of inbreeding and outbreeding. The important point is that with human marriage patterns, as with kinship systems and inheritance patterns, analyses based on cost-benefit assessments from a Darwinian model are called for, and they are feasible.
The glucocorticoid response in a free-living bird predicts whether long-lasting memories fade or strengthen with time
The glucocorticoid response in a free-living bird predicts whether long-lasting memories fade or strengthen with time (Dec 2016)
Blake Carlton Jones,
Sara E. Bebus
Stephen M. Ferguson,
Philip W. Bateman,
Stephan J. Schoech
For decades, scientists have used threat conditioning (traditionally termed ‘fear conditioning’) to study the link between glucocorticoids and the consolidation of long-term memories (i.e. memories that last hours to weeks) in model organisms in the laboratory. We assessed this relationship in a free-living species, and examined a possible relationship between glucocorticoids and the retention of long-lasting memories (i.e. memories that last months to a lifetime). We developed a novel threat-conditioning protocol by which free-living Florida scrub-jays, Aphelocoma coerulescens, were either chased by a novel predator or exposed to a control. We measured flight initiation distance (FID) 48 h, 11 months and 2 years after conditioning or control exposures, and compared these measures to levels of stress-induced glucocorticoids. Conditioned subjects maintained significantly longer FIDs for at least 2 years. Furthermore, the long-term memory consolidation of conditioned subjects positively correlated with their stress-induced glucocorticoid response, similar to results from laboratory studies. Surprisingly, individuals with a moderate stress response exhibited an exaggerated defence response (i.e. FIDs increased) at 11 months and 2 years post-conditioning, whereas low and high stress responders exhibited memory decay or extinction (i.e. FIDs decreased). We speculate that the recently discovered processes of memory reconsolidation and system consolidation may help explain why some Florida scrub-jays exhibit more fearful-like behaviour with time.
Dienstag, 15. November 2016
Heiner Rindermann, David Becker, Thomas R. Coyle (Nov 2016)
Evolutionary framework for identifying sex- and species-specific vulnerabilities in brain development and functions; David C. Geary (Nov 2016)
Paternal age negatively predicts offspring physical attractiveness in two, large, nationally representative datasets; Michael A. Woodley of Menie & Satoshi Kanazawa (Nov 2016)
Ein paar Auszüge aus:
Fühlen, Denken, Handeln
Gerhard Roth (2001)
Fühlen, Denken, Handeln
Gerhard Roth (2001)
“Einem intelligenten Menschen unterstellt man, dass er gut und schnell denken kann, …”
[Demnach] “wäre ein intelligenter Mensch ein solcher, dem angesichts eines bestimmten theoretischen oder praktischen Problems und unter einem gewissen Zeitdruck Lösungen einfallen, auf die Durchschnittsmenschen nicht kommen.”
“Schlechte Problemlöser erkennen oft nicht, was ein Problem schwierig macht, und können ihre Strategien dem neuen Problem nicht gut anpassen. Der intelligente Mensch hingegen ist dadurch gekennzeichnet, dass er relativ schnell eine Lösung des anstehenden Problems findet. Beim Problemlösen muss nicht nur relevante Information aktiviert, sondern auch irrelevante Information unterdrückt werden, und all dies geschieht meist unter Zeitdruck. Hiernach sollte sich das Gehirn eines intelligenten Menschen dadurch auszeichnen, dass das Abrufen relevanter Information (vor allem von »Expertenwissen«), das Unterdrücken irrelevanter Information sowie das anschließende Zusammenfügen der relevanten Information möglichst schnell und mit möglichst geringem Aufwand geschieht.”
“Patienten mit Stirnhirnerkrankungen [sind] oft unfähig, in einer Situation und bei einem Problem Relevantes von Irrelevantem zu unterscheiden. Auch haben sie starke Defizite in der für das Problemlösen wichtigen Fähigkeit, die Perspektive zu wechseln und nach alternativen Strategien zu suchen. Frontalhirn-Patienten verweilen oft hartnäckig bei einer Strategie und lassen sich durch ihr eigenes Versagen nicht beeindrucken.”
“Die meisten von uns leiden an irgendeiner Begrenzung von Gedächtnisleistungen. Wer wünscht sich nicht ein besseres Gedächtnis? Tatsächlich bringt aber ein wirkliches »Supergedächtnis« keineswegs nur Vorteile, denn dies bedeutet keineswegs bloß, dass man sich an alles erinnern kann, wenn man nur will, sondern dass man auch ganz unwichtige Dinge nicht vergessen kann. Ein Supergedächtnis vermag in aller Regel nicht oder nicht gut zwischen »wichtig« und »unwichtig« zu unterscheiden, für es ist nahezu alles »wichtig«, d. h. erinnerungswürdig.”
Dienstag, 8. November 2016
You often hear advice from successful people that you should “follow your passion.” That sounds perfectly reasonable the first time you hear it. Passion will presumably give you high energy, high resistance to rejection, and high determination. Passionate people are more persuasive, too. Those are all good things, right?
Here’s the counterargument: When I was a commercial loan officer for a large bank in San Francisco, my boss taught us that you should never make a loan to someone who is following his passion. For example, you don’t want to give money to a sports enthusiast who is starting a sports store to pursue his passion for all things sporty. That guy is a bad bet, passion and all. He’s in business for the wrong reason.
My boss, who had been a commercial lender for over thirty years, said the best loan customer is one who has no passion whatsoever, just a desire to work hard at something that looks good on a spreadsheet. Maybe the loan customer wants to start a dry-cleaning store or invest in a fast-food franchise—boring stuff. That’s the person you bet on. You want the grinder, not the guy who loves his job.
So who’s right? Is passion a useful tool for success, or is it just something that makes you irrational?
My hypothesis is that passionate people are more likely to take big risks in the pursuit of unlikely goals, and so you would expect to see more failures and more huge successes among the passionate. Passionate people who fail don’t get a chance to offer their advice to the rest of us. But successful passionate people are writing books and answering interview questions about their secrets for success every day. Naturally those successful people want you to believe that success is a product of their awesomeness, but they also want to retain some humility. You can’t be humble and say, “I succeeded because I am far smarter than the average person.” But you can say your passion was a key to your success, because everyone can be passionate about something or other. Passion sounds more accessible. If you’re dumb, there’s not much you can do about it, but passion is something we think anyone can generate in the right circumstances. Passion feels very democratic. It is the people’s talent, available to all. ...
Scott Adams (2014)
Sonntag, 6. November 2016
Mittwoch, 2. November 2016
"People don’t acquire vocabulary by rote learning. They don’t memorize word lists and definitions by drill and repetition. Virtually all of one’s vocabulary is acquired by hearing or reading words in a context from which one can infer their meaning. One might have to encounter a word used in several different contexts to be able to infer its complete meaning and its subtle difference from some similar word (e.g., charitable and generous). Brighter persons infer more of a word’s meaning from any given context and don’t need as many encounters with it in different contexts to grasp its distinctive meaning. Given similar amounts of exposure to the language, therefore, a more intelligent person acquires a larger, qualitatively richer, and more subtle vocabulary than a less intelligent person."