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.     

Novel popout with nonsense strings: Effects of predictability of string length and spatial location

Recent studies have shown that when one of four expected words is replaced by a single unexpected word, the unexpected word may capture attention. In three experiments, we explored the generality of this effect. In each experiment, observers viewed arrays composed of four computergenerated “nonsense” strings. Accuracy of string localization was assessed after each array. Some strings, calledfamiliar, appeared in many arrays, whereas others, callednovel, appeared in only one. In each experiment, novel strings in arrays composed of one novel and three familiar strings were localized more accurately than were novel strings in arrays composed entirely of novel strings, and familiar strings in these arrays were localized less accurately than were familiar strings in arrays composed entirely of familiar strings. These two effects, termednovel popout andfamiliar sink-in, respectively, were observed even when novel and familiar strings were rendered less discriminable by holding their lengths constant (Experiment 2) and when familiar strings always appeared in the same spatial locations (Experiment 3). The data suggest that novel objects can capture attention even when the objects lack any clear linguistic referent, when they are superficially similar to the familiar objects that surround them, and when the spatial locations of familiar objects are completely predictable.     

Expectations regarding acquaintance sexual aggression among sorority and fraternity members

Among women, college is a high risk period for sexual assault by male acquaintances. Differences in expectations held by men and women may contribute to misinterpretation of social cues and subsequent sexual aggression and may impair women's ability to respond effectively. This paper presents findings from a predominantly Caucasian sample (85.9%) of college sorority (n = 66) and fraternity (n = 34) members regarding the social context within which they interact and their expectations regarding perpetration of and response to sexual aggression. Results showed differences in men's and women's expectations and responses, and in particular highlighted how men's expectations were related to women's resistance of unwanted sex. Understanding the cognitive processes that men and women draw upon in social interactions can be useful for developing sexual aggression prevention and resistance interventions.An earlier version of this paper was presented at the Council on Social Work Education Annual Program Meeting, March 1995, San Diego. The authors would like to thank Robert D. Abbott, Kelly Cue, and Virginia Senechal for their input on earlier versions of this paper.This project was jointly supported by the University of Washington Alcohol and Drug Abuse Institute, School of Social Work, and Addictive Behaviors Research Center. It was also supported in part by grants from NIAAA (AA05591 and AA07271) and NIMH (MH53702).     

The morphological asymmetry of the hemispheres and cerebral dominance for speech: A possible relationship

The asymmetry of the posterior Sylvian branches of the middle cerebral artery was examined on the carotid angiograms of 59 patients in whom the lateralization of speech representation was known from sodium amobarbital (Amytal) studies. The usual asymmetry of these vessels was found to be present in the group of patients with left-hemisphere speech representation but significantly reduced in patients with atypical cerebral dominance for speech. A model of the inheritance of handedness and cerebral dominance is extended to take account of these results.     

Visual processing of multielement arrays and selective backward masking

In the first of two selective masking experiments, 7-letter rows were followed at several ISIs by a mask or no-mask and a bar-marker partial report cue. The results suggest that the arrays were processed ends-first and then, in general, from both ends towards the middle. In the second experiment, bar-marker partial report cues were presented at the onset or offset of 6-letter/1-digit or 7-letter rows. The subjects could not anticipate the category of the to-be-reported item with the alphanumeric displays. With a delayed cue, selective masking was obtained with both mixed category and pure letter arrays, but with simultaneous cuing, masking was always distributed across all serial positions. The results suggest that the subjects: (a) abstracted some information about category from the mixed arrays during an initial parallel stage of processing, (b) selectively attended to mainly the cued item with simultaneous probes with homeogeneous and mixed category displays, and (c) employed an ends-first processing strategy with both types of arrays when the bar-marker partial report cue was delayed.