Attachment behavior: a validation study in two age groups.

To assess the validity of attachment scores derived from the Ainsworth "strange situation," 56 1-year-olds and 79 2-year-olds accompanied by either the mother, the father, or a brief acquaintance were studied. Proximity to the adult, duration of play, crying, activity, and the incidence of looks and distance bids were measured. 1-year-olds were more secure with their parents: they were more active, played more, cried less, and stood closer to their parents than to an acquaintance. 2-year-olds accompanied by their parents were less settled in the presence of a stranger than children accompanied by the acquaintance. The adequacy of current conceptions and measures of attachment was discussed in light of these results.     

Dimensional salience and judgments of bigness by three-year-old children.

3-year-olds were shown triads of rectangles and asked to select the "big" one, where the biggest rectangle in each triad was neither the tallest nor the widest. Dimensional salience and response choice were highly related. In addition, as saliency of a particular dimension increased relative to the other dimension, significantly more responses were based on that dimension. The results support the notion that the young child does not rely on 1 specific dimension to make judgments of bigness but, rather, attends to the most salient differences among stimuli.     

Reversal of visual discrimination problem and differential frustration effects in dominant and submissive rats

Two experiments are reported comparing performance in dominant and submissive rats as determined by a food-competition procedure. Ss in Experiment I were either trained to criterion or overtrained before being reversed on a visual discrimination task. Although the two groups did not differ significantly in learning the initial task, the dominant Ss were significantly slower on reversal than the submissives. Experiment II, which utilized a tandem runway, showed that when the reinforcer which maintained the running response was not available in the first goalbox, submissive rats responded with a greater increase in running speed in the second runway than dominant rats. These findings were discussed as reflecting motivational differences between dominant and submissive rats.     

Successive acquisition and extinction in a runway with the domestic Muscovy duck (Cairina moschata)

Twenty domestic Muscovy ducks were trained to traverse a runway for food reward. Subjects were then randomly assigned to treatments. In one treatment, subjects received six nonrewarded trials followed by six rewarded trials every day for 12 days; and, in the other treatment, subjects received six rewarded trials followed by six nonrewarded trials every day for 12 days. These successive acquisition and extinction (SAE) treatments were selected because different extinction rates on the nonrewarded trials are expected on the bases of previous research performed with rats. Analyses of variance revealed the former treatment yielded significantly greater resistance to extinction than did the latter treatment. It was concluded that ducklings performed similarly to rats in the above SAE situation.     

Self-punitive responding in rats with goal shock and color change

After acquisition avoidance training, rats were assigned on the basis of matched run speed to the following groups: (1) maintenance of avoidance training, (2) extinction procedures with the addition of a brief shock in the goalbox, and (3) regular extinction procedures. Each group was further divided into two minor groups which experienced either change or no change in goalbox color. The results indicated : (1) that self-punitive responding was increased by goal shock, (2) that self-punitive responding was reduced by goalbox color change, and (3) that generalization of goal shock to the startbox and runway areas is a factor in self-punitive responding.     

A developmental analysis of the relationship between response strength and punishment

Two levels of training (100 vs. 500 trials) and two ages of rats (young and adult) were used in a developmental analysis of the relationship between response strength and the effects of punishment. The apparatus was a Y maze with three discriminably different arms. After 100 or 500 reinforced trials, subjects were shocked each time they responded in one arm. The recovery sessions followed the punishment session. Results from the punishment day indicated that: (a) young rats received a greater amount of shock, and (b) additional training increased the amount of shock received by the young but decreased it in the adults. The recovery data showed that: (a) the suppressive effects of punishment were greater for the adults than for the young, and (b) the recovery scores were not influenced by degree of overtraining. The Age by Overtraining interaction suggested that the relationship between response strength and punishment is age dependent. The age differences found with the amount-of-shock and recovery measures provided additional support for the position that younger rats are less competent than adult rats in inhibiting responses.