Sniffy,the virtual rat: Simulated operant conditioning

We report on the use of our Sniffy program to teach operant conditioning to 900 introductory psychology students. The simulation is designed primarily to teach the principles of shaping and partial reinforcement in an operant chamber. Advanced features are provided for exploring modeling issues and the learning parameters of the model. Students observe the rat’s pretraining behaviors, shape barpressing, and explore the effects of partial reinforcement schedules on a cumulative record. Any of 30 actions can be trained to occur in specific locations in the Skinner box. This paper summarizes details about the software, interface, and instructional objectives.     

Sensorimotor synchronization: Motor responses to pseudoregular auditory patterns

Musically trained and untrained subjects (N=30) were asked to synchronize their finger tapping with stimuli in auditory patterns. Each pattern comprised six successive tonal stimuli of the same duration, the first of which was accented by a different frequency. The duration of interstimulus onset intervals (ISIs) gradually increased or decreased in constant steps toward the end of the patterns. Four values of such steps were used in different trials: 20, 30, 45, and 60 msec. Various time-control mechanisms are hypothesized as being simultaneously responsible for subjects’ incorrect reproduction of the internal temporal ratios of the stimulus patterns. The mechanism of assimilation (of a central tendency) led subjects to enforce a regular (isochronous) structure on the patterns. The influence of other time-control mechanisms (distinction, subjective expression of an accent, sequential transfer) was expressed mainly in differences between intertap onset intervals (ITIs) and the corresponding ISIs at the beginning of the patterns. The duration of the first two ITIs was in the majority of the trials in an inverse ratio to the ratio of the respective ISIs. The distortions resulting from the timing mechanisms concerned were more pronounced in the performance of nonmusicians than in that of musicians.     

Human sensitivity to temporal proximity: The role of spatial and temporal speed gradients

Estimates of temporal proximity (sometimes called time-to-collision) from random-dot flow patterns are shown to be based upon retinal speed, rather than upon changes in dot density. Neither the spatial nor the temporal gradient of motion is essential to the task, but estimates can be made from either alone. Performance is unaffected by the addition of rotational motion, suggesting that observers axe capable of extracting the radial component of motion, which contains all the relevant information, from complex stimuli.     

Antecedents and Consequences of Victimization of Lesbian, Gay, and Bisexual Young People: A Structural Model Comparing Rural University and Urban Samples

Research indicates that antigay victimization is widespread and that lesbian, gay, and bisexual young people may be very vulnerable to such victimization. The current study builds upon previous work by Hershberger and D'Augelli (1995), who studied the consequences of sexual orientation-based victimization in 194 urban lesbian, gay, and bisexual youths. Using structural equation modeling, the present study models both antecedents and consequences (including psychological distress, self-esteem, and suicidality) of victimization via a secondary analysis of their data set. In addition, a second sample of 54 lesbian, gay, and bisexual youths from a rural university setting was examined to cross-validate and generalize the relationships found in urban settings. Results indicated that a revised model of victimization exhibited sufficient fit to the urban sample data and provided preliminary support for the generalizability of the model beyond the initial sample. Additional similarities were found between the urban and rural university community samples, including a high prevalence of reported suicide attempts: 42% of the urban sample and 32% of the rural university sample had attempted suicide at least once. Results indicated that victimization based on sexual orientation has similar correlates for young people in different community settings.     

THE SEXUAL HARASSMENT OF MEN?

Recently the focus of sexual harassment research on the harassment of women by men has been challenged. Treatments of sexual harassment of men, however, have generally ignored power differentials between the genders. Our analysis predicts that behaviors identified as harassing by men stem from negotiations of gender in the workplace that challenge male dominance, whereas behaviors experienced by women as sexually harassing reinforce female subordinance. Consistent with our predictions, results indicated the following: men are considerably less threatened than women are by behaviors that women have found harassing; men find sexual coercion the most threatening form of harassment; men as well as women sexually harass men; and men identify behaviors as harassing that have not been identified for women. Results also showed signs of backlash among men against organizational measures that address sexual harassment and discrimination against women. Implications for psychological and legal definitions of sexual harassment of men are discussed.     

The power of faces: A review of John T. Lanzetta's research on facial expression and emotion

Provides a comprehensive review of John T. Lanzetta's research program on facial expression and emotion. After reviewing the study that initiated this research program (Lanzetta & Kleck, 1970), the program is described as developing along four distinct lines of research: (1) the role of facial expression in the modulation and self-regulation of emotion, (2) the evocative power of the face as an emotional stimulus, (3) the role of facial expression in empathy and counterempathy, and (4) the role of facial displays in human politics. Beyond reviewing the major studies and key findings to emerge from each of these lines, the progression of thought underlying the development of this research program as a whole and the interrelations among the individual research lines are also emphasized.     

Reaction-anticipation transitions in human perception-action patterns

We investigated the hypothesis that reaction and anticipation in human perceptual-motor performance are two coordinative modes of a single pattern-forming dynamical system, rather than separate behaviors. Subjects coordinated the onset of finger flexions with visual metronome flashes in each of three patterns: reactive, synchronized, or syncopated. The stimulus frequency was progressively increased (0.125–1.375 Hz) or decreased (1.375-0.125 Hz) in small steps (0.125 Hz) every 10 cycles. We observed qualitative transitions in both the time interval between stimulus and corresponding action (Δt) and their relative phase (ø) at critical values of the stimulus frequency, corresponding to changes from ‘reactive-to-anticipatory’ and ‘anticipatory-to-reactive’ performance. Such transitions provide evidence of a single, multifunctional system, which can be adequately described by the dynamics of collective variables characterizing the respective perception-action patterns.     

Validation of a full body 3-D dynamic linked segment model

In studies related to human movement, linked segment models (LSM's) are often used to quantify forces and torques, generated in body joints. Some LSM's represent only a few body segments. Others, for instance used in studies on the control of whole body movements, include all body segments. As a consequence of the complexity of 3-dimensional (3-D) analyses, most LSM's are restricted to one plane of motion. However, in asymmetric movements this may result in a loss of relevant information. The aim of the current study was to develop and validate a 3-D LSM including all body segments. Braces with markers, attached to all body segments, were used to record the body movements. The validation of the model was accomplished by comparing the measured with the estimated ground reaction force and by comparing the torques at the lumbo-sacral joint that resulted from a bottom-up and a top-down mechanical analysis. For both comparisons, reasonable to good agreement was found. Sources of error that could not be analysed this way, were subjected to an additional sensitivity analysis. It was concluded that the internal validity of the current model is quite satisfactory.     

Merleau-Ponty,Marx, and Marxism: The problem of history

At the present time, Europe, particularly eastern Europe, is still immersed in a major political transformation, the most significant such change since the Second World War, arising out of the rejection of official Marxism. This unforeseen rejection requires meditation by all those concerned with the relation of philosophy to the historical context. Marxism, that follows Marx’s insistence on the link between a theory and the context in which it arises, cannot be indifferent to the rejection of Marxist theory in practice. In respect to the usual tendency to pass rapidly over practice for a theoretical analysis of social theory, Merleau-Ponty stands out for his concern to evaluate the theoretical claims of Marx and Marxism against practice.