A role for stimulus generalization in conditional discrimination learning

In each of three experiments on discrimination learning by rats, whether or not a 10-sec target stimulus was followed by food was determined by the nature of a 2-min background stimulus that accompanied it. A conditional discrimination was employed in Experiment 1 such that background A indicated food would follow one target but not the other, whereas this relationship between the targets and food was reversed in the presence of background B. Experiment 2 employed two feature-positive discriminations. Subsequent test trials revealed that the background for one discrimination was able to enhance responding during the target for the other discrimination. Experiment 3 employed a feature-positive and a feature-negative discrimination prior to test trials in which each target was presented separately during a compound of both background stimuli. The compound enhanced responding to the target from the feature-positive discrimination and reduced it to the target from the feature-negative discrimination. We suggest that to accommodate all these findings, the best explanation is provided by a configural model of Pavlovian conditioning.     

Selective transfer of responding in conditional discriminations

In each of three experiments rats received discrimination training in which whether or not a 10-sec target stimulus was followed by food was signalled by a 2-min background stimulus. In the first experiment the target was paired with food in the presence but not the absence of the background stimulus. Subsequent tests revealed that the background elevated responding to a target that had taken part in a similar discrimination. However, it had no influence on the responses elicited by a partially reinforced conditioned stimulus. In the remaining experiments the target was paired with food in the absence but not the presence of the background. Test trials then revealed that although the background had an inhibitory influence on the responses elicited by a target from a similar discrimination, it had no influence on the responses elicited by either a partially or a continuously reinforced conditioned stimulus. Various explanations for this selective influence of a background stimulus are considered.     

Cardiovascular responses to occupational stress in male medical students: a paradigm for ambulatory monitoring studies.

Hemodynamic responses to systematic variations in occupational stress were examined using ambulatory blood pressure monitors (ABPMs). The goals of this study were (a) to illustrate the effectiveness of employing naturally occurring, controlled variations in psychological stress levels in studies incorporating ABPMs and (b) to document the patterns of cardiovascular responses to acute examination stress in medical students. Heart rate, systolic blood pressure, diastolic blood pressure, rate-pressure product, and mood states were measured before, during, and after low-stress (lecture) and high-stress (examination) work in 44 healthy male medical students. The lecture day was characterized by stable patterns of cardiovascular activity across all three periods. Hemodynamic activity and reports of activation and distress were greater on the examination day than on the lecture day. Cardiovascular activity during the preexamination period was as high as that seen during the examination period itself, indicating an anticipatory stress effect. Pressor activity decreased after the examination, although some residual chronotropic activity was seen. Systematic changes in physiological responses to controlled variations in the level of this naturalistic stressor support the use of this paradigm for other ABPM studies. The elevations in preexamination responses seen here suggest the need to consider prestressor experiences in such studies.     

Perceiving Multiple Affordances for Objects

Researchers (Gilden &; Proffitt, 1989; Runeson &; Vedeler, 1993; Todd &; Warren, 1982) have tested Runeson's (1977) claim that the relation between a collision . . event's dynamics and kinematics might support perception of the relative mass of colliding objects. Results have been inconsistent; however, these studies employed computer-generated collisions as stimuli. The present research assessed observer's ability to report relative mass in the context of physical objects involved in physical collisions. The results indicate greater sensitivity to relative mass than had been found with animations-based studies. Implications of these data for the kinematic specification of dynamics (KSD) principle of dynamics perception (Runeson &; Frykholm, 1983) and a cue-heuristics theory of dynamics perception (Gilden &; Proffitt, 1989) are discussed.     

Melancholia and the Violent Regulation of Gender Variance: Reply to Commentaries

In this reply to James Herzog and Gayle Salamon, the “in”/“out” boundary of gender and the psychotherapeutic address of gender is considered. Particular emphasis is paid to the ways in which gender is constituted through aggressive and often violent forms of social regulation. Matters of social justice are considered as psychoanalysts and mental health workers take up normative violence in the form of policy speech. Clinical dilemmas with respect to gender melancholia, trauma, and shame are also considered.     

More Life: Centrality and Marginality in Human Development

At both ends of the century, a border between the aberrant-marginal them and the ideal-central us has been constructed around and through the homosexual. I challenge the insufficiency of this characterization, so that we may learn more, not only about homosexuality, but also about the ways in which all human development is infused with an interplay between centrality and marginality. I argue that traditional developmental models are dominated by the normative logic of centrality, with limited accounting for the developmental necessity of marginality, whereas postmodern theories of subjectivity overvalue the potential of the margin and fail to account for the significance of similarity and coherence in human relations. I then use that criticism as a platform for proposing five quasi-axioms toward a new developmental model. Central to this new model, which employs constructs derived from chaos and systems theories, is the interplay of centrality and marginality in any given life.