Detecting and identifying change: additions versus deletions

The recognition of changes in the features of objects was examined as a function of the nature of the change (additions, deletions, no change). In two experiments we assessed both detection (noticing whether the stimulus had changed) and identification (specifying the exact nature of the change). Both detection and identification were expected to depend upon the subject's awareness of the subsequent recognition tasks while the original stimuli were encoded. In Experiment 1, subjects were not aware of subsequent detection and identification tasks while they initially viewed study slides of the to-be-changed stimuli. During the subsequent presentation of the test stimuli, detection and identification were superior for additions. On the other hand, in Experiment 2 when subjects were aware of the subsequent recognition tasks while viewing each study slide, a detection advantage for deletions obtained. Identification performance depended upon a further factor, whether the features of a stimulus were codable. Only in codable stimuli were deletions easier to identify than additions. The differences between the two experiments in detecting and identifying additions versus deletions are consistent with Tversky's (1977) research that stresses the importance of specifying which representation (the study stimulus or the test stimulus) is the subject of comparison in the comparative judgment.     

Group coleadership: a new role for parents of adolescents with anorexia and bulimia nervosa

This paper describes a model for coleadership of a multifamily group which is part of an outpatient treatment program for adolescents with anorexia and bulimia nervosa at The Children's Hospital in Boston. This clinic is a collaborative effort between the Departments of Psychiatry and Adolescent Medicine and has been involved with more than 600 patients and their families. The parents of a recovered adolescent girl have shared group leadership with the author for six years and have added an innovative dimension to the group process as a result of their own experiences. Theoretical and empirical observations are presented and guidelines for maximizing coping abilities are outlined.     

Stability over age and sex of children's responses to embedded figures test

240 children in Grades K to 4 were administered the entire Children's Embedded Figures Test to determine whether similar factor structures are obtained from samples of different sex and age as well as when the population is randomly split. Data were analyzed by principal axis factor analysis and relevant factor structures were compared using Veldman's 1967 program "Relate". There was one stable factor which was consistent across sex and accounted for about 19% of the variance. Results were inconsistent across grades and indicated a possible lack of agreement of factor structures.     

Generalization and discrimination of shape orientation in the pigeon

Pigeons learned to peck a green key on which parallelogram-shapes were projected; they then received generalization tests in which the orientation of the parallelogram was varied. Nondifferential training produced very little eventual stimulus control along the orientation dimension, but when training included S- trials (absence of the parallelogram) subjects responded consistently more to certain orientations than to others. Unlike typical results for visual generalization (e.g., line-tilt), the tilt gradients obtained for this complex stimulus were bimodal, supporting predictions on the basis of human perceptual data. However, unimodal gradients could be produced by specific discrimination training along the orientation dimension. Other forms of intradimensional training also produced relatively steep gradients, often characterized by unexpected but consistent secondary peaks. An attempt to obtain inhibitory gradients (S+: green key; S-: parallelogram on a green background) resulted in virtually zero responding all along the shape-orientation dimension; therefore, specific inhibitory control could not be evaluated. All these experiments suggest that definition of this complex stimulus dimension in terms of mere "angular orientation" is inappropriate, and alternative interpretations are discussed.     

Stimulus intrusion on fixed-interval responding in the rat: The effects of electric shock intensity,temporal location,and response contingency

After a scalloped lever-press response pattern had developed under a fixed-interval food reinforcement schedule, a 15-sec electric shock was intruded for different groups of rats in the first, second, third, or fourth quarter of each inter-reinforcement interval. Shock intensity was systematically increased for individual rats over 70 sessions, from 0.05 to 1.6 mA. Additional between-groups comparisons involved response-dependent versus clock-dependent fixed-interval schedules, and response-dependent versus response-independent electric shock intrusion. Response rates within each fixed interval prior to, during, and following electric shock intrusion showed regular and reproducible increases and decreases under systematic application of the experimental variables. These results provide further evidence that the functions of a stimulus are determined in part by the parameters of intensity, response contingency, and temporal location with respect to reinforcement.     

Desiring and expecting to work among high school girls: Some determinants and consequences

The effects of mother's and father's work status and of social-psychological intervening variables on high school girls' orientation to the labor force are examined. The dependent variables are separate indicators of whether the girls want and whether they expect to have an occupation. In these data from 1965, a log linear analysis shows that whether the mother worked was the major background influence on the dependent variables; father's occupation had no significant independent effect. In addition, two “ideological” variables, the girl's identification with the mother and beliefs in individual achievement, strongly influenced the dependent variables, in a way that did not merely mediate the background effects. Finally, some consequences of wanting and/or expecting to work are examined, and it is argued that the choice of career pattern (housewife versus paid employment) was a central one in girls' attitudinal structures.     

Food delivery as a conditional stimulus: Feature-learning and memory in pigeons

Three experiments investigated the learning and memory of discriminations based on presence versus absence of a pre-trial food delivery. In Experiment 1 half the illuminations of a response key were followed by food regardless of the subject's behavior. In one group an extra food delivery preceded only reinforced trials (feature-positive condition), whereas in a second group it preceded only nonreinforced trials (feature-negative condition). Key pecks and approaches revealed more rapid and superior discrimination learning in the first group. Experiment 2 replicated the results of Experiment 1 but yielded no evidence that greater “unexpectedness” of pretrial food conditions facilitates discriminative performance. In Experiment 3, individual pigeons trained on a conditional discrimination exhibited a within-subject feature-positive superiority. Delay between pretrial and trial stimuli interacted with feature-positive versus feature-negative training in both the between-group (Experiment 2) and within-subject (Experiment 3) procedures: performance was decremented at both short and long delays in the feature-positive condition but was decremented only at longer delays in the feature-negative condition. The feature-positive superiority obtained here is incompatible with explanations based on either the general concept of “perceptual organization” or on the conditional nature of feature-negative discriminations.