A clarification of frequency effects in children’s discrimination learning

Memory & Cognition - Three experiments were conducted to assess the effects of certain stimulus variables on children’s discrimination learning. In general, it was found that word...     

Limulus psychophysics: dark adaptation in the ventral eye.

Sudden illumination applied to Limulus produces an unconditioned downward tail movement which is under stimulus control and can be used to measure psychophysical thresholds. The method of constant stimuli was used to measure the behavioral dark-adaptation function mediated by the ventral eye of Limulus. The resulting function has two phases, each of which is rectified when log threshold is made a function of long time in the dark. Under the conditions of the present experiment, the transition between the two phases occurred at 6 min. This psychophysical dark-adaptation function has the same form as an electrophysiologic dark-adaptation function obtained by Fein and DeVoe (using the ventral eye receptor potential as the response). In more complex visual systems such two-phase, dark-adaptation functions would usually be interpreted in terms of screening pigment movements or changes in the neural contributions of different receptor classes, but neither interpretation is appropriate for the ventral eye of Limulus.     

The disruption of autoshaped key pecking in the pigeon by food-tray illumination

Two experiments investigated the effect of food-tray illumination on pecking a lighted key that signalled food presentation. Pigeons key pecked less when both feeder and key stimuli preceded grain delivery than when the keylight alone signalled food. This detractive influence of grain-tray illumination did not result after prior pairings of the keylight with food. The involvement of associative and physical variables in autoshaping the pigeon's key peck is considered in light of these findings.     

Gender differences in moral development

Sixty-nine Midwestern middle-class children and adolescents were tested on justice and care orientations when reasoning abstract and interpersonal moral dilemmas. Nona Lyons' (“Two Perspectives on Self, Relationships and Morality,” Harvard Educational Review, 1983, 53, 125–145) scoring method was used to score subjects' responses. A 2(sex)×2(age) analysis of variance run on the total justice and care scores, as well as each individual dilemma, supported Carol Gilligan's (In a Different Voice: Psychological Theory and Women's Development, Cambridge, MA: Harvard University Press, 1982) theory that two distinct ways of thinking about moral problems exist — justice and care — and are differentially related to gender. Girls emphasized the morality of care significantly more than justice. Contrary to Gilligan (1982) and Lyons (1983), however, boys in both age groups emphasized the morality of justice and care equally. Data from the interpersonal dilemmas using Lyons's (1983) coding scheme are consistent with J. Piaget (The Moral Judgement of the Child, New York: Free Press, 1966) and Lawrence Kohlberg [“The Cognitive-Developmental Approach,” in D. A. Goslin (Ed.), Handbook of Socialization Theory and Research, Chicago: Rand McNally, 1969]: older subjects became more justice oriented and younger subjects emphasized the morality of care. Sex differences on Kohlberg's stage theory were not significant and the protagonist's gender in the Heinz dilemma had no effect on moral reasoning.     

Perceived duration,visual persistence,and neural integration

Varying stimulus intensity while measuring the perceived duration/visual persistence of brief light flashes has yielded disparate results. Some studies have found a direct relationship between the two variables; others have found an inverse relationship. Several models have been suggested to unify this behavioral literature. They invoke the absolute intensity and the nature of the judgment as explanatory variables. We now present physiological data whose analysis was motivated by these models. We measured the duration of photoreceptor potentials as a function of light intensity and response measure. One response measure was. the length of time required for the response to decline from the peak by a criterion amount. The other response measure was the length of time a response stayed above a criterion level. These data suggest that each behaviorally based model captured a different aspect of a single underlying mechanism and that a melding of the two critical concepts would harmonize all of the results: In this melding, the sensory signals that mediate visual perception would have the type of complex intensity- and time-dependent properties found in real neural responses.     

Intensity dependence of perceived duration: data, theories, and neural integration

Evaluates 2 theoretical models suggested to explain studies of the effect of stimulus intensity on the perceived duration of brief light flashes. Some studies found a direct relationship between the 2 variables; others found an indirect relationship. Each model suggests that an additional variable interacts with stimulus intensity. Proposed variables have included the nature of the judgment and the absolute intensity. The present evaluation indicates that both of the proposed variables play a role and that a melding of the models could best account for this phenomenon. The melding incorporates known time- and intensity-dependent characteristics of neural integration into the behavioral performance. The evaluation also indicates that future experiments on this problem will be most informative if they (a) give particular attention to the role of instructions, (b) explore an adequate range of intensities, and (c) strictly control adaptive state.     

Object knowledge and the emergence of language

Infants' spontaneous play with objects was examined for evidence of developments in object knowledge in relation to the emergence of words and the single-word period in language development. Subjects were 7 girls and 7 boys, from different ethnic and economic backgrounds, who were studied longitudinally from 9 months to 26 months of age. Two types of displacements of objects in relation to one another were identified in the children's play: separations and constructions. The development of constructions was associated with the emergence of words, and constructions increased with age while separations decreased. The development of specific constructions, which account for knowledge of the particular properties of objects, was more strongly associated with a vocabulary spurt at the end of the single-word period than with chronological age. Despite the wide variation in the infants' ages when developments in language and play were reached, relations between achievements in the two domains were consistent among them, as confirmed with the Friedman test, p<.001. The results are discussed in terms of the cognitive developments required for play with objects and saying words.     

Detection and identification thresholds for consonant-vowel syllables

Detection and identification thresholds were obtained for 6- and 10-year-old normal children and normal adults using five-formant synthesized consonant-vowel ([baHdflrfea]) stimuli. Sixyear-old children were found to have poorer detection than adults, just as they do for pure tones. For the identification task, the slopes of the performance-intensity functions were more shallow for 6-year-old children than for 10-year-olds and adults. Consequently, compared with 10-yearolds and adults, 6-year-old listeners require a greater increase in stimulus intensity above detection threshold to identify these stimuli at a high performance level. The influence of acoustic characteristics of the stimuli on all listeners is also discussed.     

Further remarks on the role of cognition in the comparative analysis of behavior

Recent interest in comparative psychology has stimulated much research and debate concerning cognitive processes in animal behavior. The present paper relates to this general area by treating particular issues in the analysis of comparative cognition: specifically, how cognition is inferred from animal behavior; whether the postulation of intervening cognitive processes furthers our understanding of behavior; and how rival approaches help advance the science of behavior.