A cusp catastrophe: Hysteresis, bimodality, and inaccessibility in rabbit eyelid conditioning

Three properties of the cusp catastrophe: bimodality, inaccessibility, and hysteresis were evaluated in rabbit eyelid conditioning. Bimodality was evidenced by the fact that responding tended to occur at either very low or very high levels, and inaccessibility by the fact that intermediate levels of responding were rarely encountered. Hysteresis was demonstrated when: (a) levels of responding attained under a continuous schedule of reinforcement were largely maintained by a schedule which was too lean to promote conditioning by itself; and (b) levels of responding attained with a high intensity unconditional stimulus were largely maintained by a lower intensity unconditional stimulus which was too weak to promote conditioning in its own right. These results are consistent with the model of conditioning suggested by P. W. Frey and R. J. Sears (Psychological Review, 1978, 85, 321–340) which postulates response-mapping rules based on the cusp catastrophe.     

Coactor's behavior and imitative aggression

After being exposed to either an aggressive or a nonaggressive filmed model, four- and five-year-old boys were tested for imitation while either alone or with a confederate who had also seen the film. The confederate's behavior was either inactive, the same as that in the film, the same as that in the film the child had not seen, novel but of the same category (aggressive or nonaggressive) as that in the film seen, or novel but in the category of the film not seen. These conditions conformed to the dimensions of a 2 × 6 factoral design. According to prediction, the imitation of subjects exposed to the aggressive model was greatest when the confederate's behavior was similar to the model's. No difference in imitation was produced by the confederate's actions if the boy had watched the nonaggressive model. The results were interpreted within the context of social comparison theory.This project was facilitated by the senior author's Margaret Bosshardt Pace and Paul David Pace Research Fellowship.     

THOG: The anatomy of a problem

Summary Three experiments are reported on the attempts to solve a novel hypothetico-deductive problem. Its solution demands both the postulation of hypotheses about its structure and a combinatorial analysis upon the consequences of these hypotheses. The majority of subjects (students) failed to solve the problem because they argued from the properties of stimuli rather than from hypotheses about their conceptual status. The results suggest that a familiarity with the logical structure of the problem and the elicitation of appropriate hypotheses failed to correct this intuitive approach. These findings are discussed in relation to Piaget's theory of formal operations, and (very tentatively) in relation to habitual styles of thought.     

Temporal properties of responding during stimuli that precede response-independent food

Pigeons' keypecks were reinforced with grain on the average of once per minute by schedules that maintained low response rates and by schedules that maintained high response rates. During these schedules, a fixed-duration conditioned stimulus (CS) ranging from 7.5 to 120 sec in duration across conditions terminated with response-independent food. Response rates during the CS were inversely related to CS duration. The rates and the temporal patterns of responding during the shortest CS were similar whether the ongoing schedule maintained high response rates or low response rates. As CS duration increased, the rate and pattern of responding during the CS converged on the rate and pattern of responding maintained by the baseline schedule. These data indicate that changes in responding during stimuli that signal response-independent reinforcement are not homogeneous throughout the CS; that response measures, such as “suppression ratios”, which presume homogeneity may mislead us; and that conditioned suppression and conditioned enhancement may be better talked about in terms of species-specific approach and avoidance than in terms of emotional states.     

Classifying pictures and words: Implications for the dual-coding hypothesis

In deciding that two items come from the same category, subjects were delayed if the items were presented as a word and a picture, as compared with two words or two pictures. Subjects were not delayed if the items were not to be compared. Hence, the delay appears to occur during the retrieval and comparison of know ledge about the items, not during their perceptual analysis. The results suggest that there are two distinct codes involved in the categorization of words and pictures, rather than a single code.     

Perception of syllable-final stop consonants by 2-month-old infants

Previous research has shown that infants are capable of perceiving many phonetic distinctions between initial segments of syllables. The present study demonstrates that 2-month-old infants have the ability to distinguish syllables differing only in their final segments. Infants were found to be sensitive to place-of-articulation differences for stop consonants in final segments of both consonant-vowel-consonant (CVC) and vowel-consonant (VC) syllable pairs. Contrary to previous reports for older infants (Shvachkin, 1973), there was no indication that 2-month-olds have any more difficulty with contrasts of final-stop consonant:3 than they do with initial ones.