Knowledge that Transforms

We conducted two experiments designed to evaluate the effects of normative influence on reactions to racism. The current problem of racism on college campuses provided the context for these studies. We found that exposure to strongly antiracist normative influence induced the expression of more strongly antiracist opinions, regardless of the number of influencing agents and regardless of whether persons expressed their opinions publicly or privately, than occurred following exposure to normative influence reflecting strong acceptance of racism. Overhearing others voice opinions that reflect strong acceptance of racism led persons to express less strongly antiracist opinions than when no influence was exerted.

This article considers how connectionist modeling can contribute to understanding of human cognition. J argue that connectionist networks should not be thought of as theories or simulations of theories, but may nevertheless contribute to the development of theories.

Two rhesus monkeys (Macaca mulatta) learned that the arabic numerals 0 through 9 represented corresponding quantities of food pellets. By manipulating a joystick, the monkeys were able to make a selection of paired numerals presented on a computer screen. Although the monkeys received a corresponding number of pellets even if the lesser of the two numerals was selected, they learned generally to choose the numeral of greatest value even when pellet delivery was made arrhythmic. In subsequent tests, they chose the numerals of greater value when presented in novel combinations or in random arrays of up to five numerals. Thus, the monkeys made ordinal judgments of numerical symbols in accordance with their absolute or relative values.

Little is known about the genetic and environmental etiology of the association between specific cognitive abilities and scholastic achievement during the early school years. A multivariate genetic analysis of cognitive and achievement measures was conducted for 146 pairs of identical twins and 132 pairs of fraternal twins from 6 to 12 years of age. At the phenotypic level, measures of achievement were moderately correlated with specific cognitive abilities. A multivariate model including one general factor and specific factors in the genetic and environmental matrices indicated that the phenotypic relationship between achievement and cognition was mediated primarily by genetic influences. Genetic correlations among the cognitive and achievement tests ranged from .57 to .85, shared environment correlations were essentially zero, and specific environment correlations were low (.00 to .19). We conclude that there is substantial overlap between genetic effects on scholastic achievement and specific cognitive abilities. Performance on ability measures differs from that on achievement measures largely for environmental reasons.

Correlational studies suggest that psychological stress suppresses cellular immune function in some, but not all, individuals. Here, effects of acute mental stress on lymphocyte subpopulations and T-lymphocyte mitogenesis were examined experimentally in healthy young adults. CD8 (T-suppressor/cytotoxic) lymphocytes increased in number and T-cell response to stimulation by phytohemagglutinin was attenuated following exposure to a 20-min laboratory stressor, but only in persons who also showed heightened catecholamine and cardiovascular reactions to stress. Hence, individuals differ substantially in their immunologic responsivity to behavioral stimuli, and such differences parallel (and may be predicted by) interindividual variability in stress-induced sympathetic nervous system activation.

The perceived attractiveness of stimuli to humans has been modulated by changes in cephalic blood temperature. Can similar effects be produced in animals by manipulation of hypothalamic temperature? This study examined the attractiveness and pleasure of food to rats during hypothalamic cooling or hypothalamic heating, by measuring feeding and hedonic and aversive facial reactions to taste. Hypothalamic cooling administered through a permanently implanted thermode elicited feeding. Hypothalamic heating did not. Hedonic and aversive reactions to taste were unaltered by hypothalamic cooling or heating, even for rats that ate during cooling. Hypothalamic cooling may thus potentiate the attractive quality of food without modulating basic taste pleasure.

This report presents evidence that smile production in 10-month-old infants is affected by the presence or absence of an audience for the facial display. The audience effect does not appear to be mediated by emotion. The evidence indicates that the production of facial expressions is at least partly independent of emotion and partly dependent on a social-communicative context from a very early age.

When people understand expressions that are intended nonliterally, two kinds of meaning are simultaneously apprehended: the literal meanings of the words themselves and the speaker's intended figurative meaning. Standard models of language comprehension assume that the literal meanings of figurative expressions are rejected in favor of a nonliteral meaning. I propose an alternative approach in which literal meanings are systematically used to convey figurative meanings through the process of allusion: The use of an expression to refer to entities or situations that are prototypical exemplars of culturally shared concepts and symbols. This approach provides an account of how people use and understand figurative language in general, and metaphor and idioms in particular.

Much of the information we encounter every day appears in settings that are clearly marked as fictional (e.g., novels, television, movies). Our studies explore the extent to which information acquired through these fictional worlds is incorporated into real-world knowledge. We used short stories to introduce fictional facts. The first experiment demonstrated that fictional information penetrates into judgments about beliefs, suggesting incorporation. The second experiment demonstrated, nonetheless, that representations of fictional information retain features of compartmentalization. We suggest, accordingly, that readers create hybrid representations of fictional information.

Previous research on subjects showing the two temperamental profiles called inhibited and uninhibited to unfamiliar events suggests that the two groups differ in threshold of reactivity to novelty. Hence, variation among infants in behavioral reactivity to unfamiliar events might predict later display of the two profiles. In a longitudinal study of 94 four-month-old infants, those who displayed the combination of high motor activity and frequent crying to stimulation were more fearful to unfamiliar events at nine and 14 months than infants who displayed both low motor activity and infrequent crying. This result implies that the processes that mediate early reactivity to stimulation may also influence a later preparedness to avoid or to approach unfamiliarity.