VOT discrimination by four to six and a half month old infants from Spanish environments.

Thirty 4–6.5 mo-old-infants from monolingual Spanish speaking homes were tested for discrimination of bilabial stop consonants differing in VOT. Discrimination was determined by the habituation and dishabituation of the orienting reflex as indexed by cardiac deceleration. Subjects were placed in one of three groups of ten subjects each. The three groups were used to determine whether bilabial stops with VOT values of ?60 and ?20 msec, ?20 and +20 msec or +20 and +60 msec could be discriminated. Subjects were presented eight trial blocks of ten repetitions of a CV syllable; these eight trial blocks were followed by two trial blocks of ten repetitions of a different CV syllable. The only difference between the CV syllables presented during the first eight and the last two trial blocks was the VOT value of the bilabial stop consonants. Subjects in the ?20 and +20 msec group showed no signs of being able to discriminate these stimuli while the subjects in the ?60 and ?20 msec group and the +20 and +60 msec group did. These results correspond to those reported for infants from English speaking families but do not correspond to those reported for Spanish speaking adults. Thus, the failure to find evidence of discrimination in the ?20 and +20 msec group suggests that experience has little effect in determining bilabial stop phonetic categories in 4–6.5 mo-old infants.     

A developmental study of the effects of irrelevant information on speeded classification

The study examined how well subjects were able to ignore the presence of irrelevant stimulus information as a function of age. Children aged 6, 9, and 12, as well as adult subjects sorted cards with one binary dimension relevant, and zero, one, or two dimensions irrelevant. Speed of classification was measured. Significant effects of age, sex, number of irrelevant dimensions, and relevant dimension on speed of classification were obtained, as well as a number of interactions of these variables. The most important finding was that the presence of irrelevant information interfered with the performance of the task by child subjects and that the magnitude of the interference declined with age. The results were interpreted as implying that developmental trends in attention may be most clearly demonstrated in tasks which require speeded processing of stimuli. The ease of administration of the speeded classification task, coupled with the clear developmental trends obtained, recommend this paradigm as a useful one with which to study the development of selective attention.     

Punishment persistence and sequence: Some effects of P-length and N-length in the rat

In a runway investigation, two groups of rats received partial punishment training with P-lengths of 1, 2, and 3 (Group P123) and P-lengths of 1 (Group P1), respectively. Two additional groups received partial reinforcement with N-lengths of 1, 2, and 3 (Group N123) and N-length of 1 (Group N1). An additional group was given unpunished continuous reinforcement in the runway, but received control shocks in a separate apparatus. Following training all subjects received punished extinction (shock plus nonreward). The results indicated that P-length increased resistance to punished extinction, however N-length did not have the corresponding effect. In addition, partial reinforcement did not increase resistance to punished extinction relative to continuous reinforcement. These results were interpreted within a sequential-theoretical framework.     

Father identification,achievement, and occupational behavior of rural youth

Comparisons were made between the post high school plans and the adequacy of father identification of male adolescents from rural economically deprived areas. The subjects were divided into two groups, low identification males (LIM) and high identification males (HIM) based on independent evaluators' judgments of the adequacy of their fathers. Each group's responses to a questionnaire concerning future plans and aspirations were compared. In general, the hypotheses predicting that HIM subjects have higher levels of aspiration, more self-confidence and greater satisfaction with school experiences were confirmed by the data.     

The role of overt activity in children's sentence production

Nursery schooler's abilityto associate pairs of toys was assessed under four experimental conditions: (1) control, (2) S manipulating the toys, (3) S generating a sentence, and (4) S generating a sentence while manipulating the toys. All three S-involvement conditions produced significantly better recognition performance than the control but contrary to initial predictions, the difference between the sentence-only and sentence-plus-manipulation conditions was not significant. In contrast to previous research, Ss in the sentence-only conditions had little difficulty producing sentences when asked. Of interest was the finding that the quality of sentence production was poorer in the sentence-plus-manipulation condition than in the sentence-only condition. Results are discussed in terms of the possible “conflict” produced when the child is required to engage in more than one overt activity simultaneously.     

Short-term memory in the pigeon with presentation time precisely controlled

Delayed matching-to-sample was studied in the pigeon using a procedure which precisely controlled the presentation time of the sample stimulus. Experiments 1 and 2 revealed that (a) accuracy of matching increased as a negatively accelerated function of presentation time, (b) accuracy declined when an interstimulus interval was introduced between successive presentations of the sample stimulus, and (c) the rate at which accurate matching was restored after an interstimulus interval was greatest when the initial presentation of the sample was short and the interval was long. It was concluded that a theory of STM based on the growth and decay of trace strength could account adequately for all of these findings. Experiment 3 studied trace interaction by presenting two sample stimuli first in succession and then simultaneously for choice. Predictions from trace competition theory about the specific lengths of presentation of these stimuli at which choice of the second stimulus should be 50% or deviate systematically below 50% were not supported. It appears that a recency mechanism in addition to competition is necessary to explain trace interaction effects.     

Transfer of approach responding between punishment, frustrative nonreward, and the combination of punishment and nonreward

Rats trained to make an approach response with either partial reward, intermittent punishment, or a combination of partial reward and intermittent punishment, were tested for persistence to extinction, punishment with reward, or punishment during extinction. Partial reward, alone or with punishment, produced greates resistance to extinction, while intermittent punishment, alone or with partial reward, produced greatest persistence to punishment with reward. Transfer of persistence from partial reward to punishment with reward and intermittent punishment to extinction was also demonstrated. However, partial reward alone did not increase persistence to punishment during extinction, whereas intermittent punishment and partial reward combined with intermittent punishment did increase such persistence. These results were interpreted in Amsel's (1958, 1962) conditioning-model theory by extending the hypothesized similarity of frustrative nonreward and punishment.