Contrast and undermatching as a function of reinforcer duration and quality during multiple schedules

Eight pigeons pecked keys under multiple variable-interval two-minute variable-interval two-minute schedules. In Experiment 1, the reinforcers were 2, 4, or 8 seconds access to a food magazine. In Experiments 2 and 3, the reinforcers were grains that had been determined to be most-, moderately-, or non-preferred. Both positive and negative behavioral contrast occurred when the reinforcers in one component were held constant and the duration or type of reinforcer obtained in the other component varied. Undermatching occurred when the relative rate of responding during a component was plotted as a function of the relative duration of the reinforcers in that component.     

Stimulus control of delayed matching in pigeons: Directed forgetting

Pigeons were trained in delayed matching-to-sample with two postsample stimuli. A postsample R-cue signaled that a matching choice phase would follow. A postsample F-cue signaled that a matching choice phase would not follow. Previous research found reduced matching accuracy on F-cued probe trials when comparison stimuli were presented in the choice phase. The present four experiments systematically varied the events following an F-cue to determine the conditions under which the F-cue reduces delayed-matching accuracy. When F-cues and R-cues controlled different behavior, matching on probe trials was poor. When both cues controlled the same behavior, matching on probe trials was good. This result is best explained by the theory that comparison stimuli retrieve the sample representation, but only in the behavioral context established by the R-cue. The present research supports the view that response-produced stimuli serve a contextual role in animal short-term memory.     

RESEARCH SETTINGS IN INDUSTRIAL AND ORGANIZATIONAL PSYCHOLOGY: FACTS,FALLACIES, AND THE FUTURE1,2,3

Data were collected about research issues involving laboratory and field settings through a content analysis of the 1966, 1970, and 1974 volumes of the Journal of Applied Psychology, Organizational Behavior and Human Performance, and Personnel Psychology. Four general categories of data were collected: (a) affiliation of investigators, (b) topic areas investigated, (c) settings of the research, and (d) research strategies employed. Four common beliefs of either laboratory or field advocates were contradicted by the data. First, laboratory research was found fairly frequently in the industrial-organizational literature. Second, theory and hypothesis testing were not overemphasized. Third, laboratory research was as applied as field research. Lastly, studies published by researchers with nonacademic affiliations were as likely to have been conducted in laboratory settings as field settings. Recommendations were made to use the laboratory more frequently for theory and hypothesis based research and to use a variety of research strategies in both laboratory and field settings.     

Modeling medical diagnosis: Logical and computer approaches

Conclusion In the present article I have surveyed several approaches to modeling the clinical diagnostic process. I have argued that at this point of the field's development, logics which simulate the reasoning patterns and knowledge base of expert clinicians represent research programs that are most likely to succeed. No logic of diagnosis has yet attained the status of being definitive; in spite of striking progress much more research and testing is required. On the basis of various existing logics, I have attempted to articulate a number of desiderata which an ideal diagnostic logic should satisfy. In spite of these criticisms, I would maintain that programs such as MYCIN and INTERNIST have already matured to the point where they are useful both in consultations and in teaching diagnostic reasoning.Department of History and Philosophy of Science, University of Pittsburgh, Pittsburgh, PA 15260. The author wishes to acknowledge gratefully the assistance of Drs. Jack D. Myers, Harry E. Pople, Jr., Joshua Nagin, and Randy Miller with the research that resulted in this essay and thanks to L. J. Cohen, J. F. Fries, R. N. Giere, and C. Whitbeck for comments on an earlier draft. Supported in part by training grant MB 00199-01 from the Bureau of Health Manpower (DHEW) and by the National Science Foundation and the National Endowment for the Humanities.Presented at a symposium on Philosophy and Medicine held at the American Philosophical Association's Eastern Division Meeting in Washington, D.C., December 27–29, 1978. This essay partially overlaps with an article on Problems in computer diagnosis to appear inThe Ethics of Diagnosis, H. T. Engelhardt, Jr. and S. Spicker (eds.) Dordrecht: D. Reidel, forthcoming.     

The development of automatic word recognition and reading skill

The development of automatic word recognition as a function of reading skill was investigated in three experiments using the Stroop task. Reading skill level ranged from nonreaders to readers above the sixth-grade equivalent. Interference with color naming begins to emerge early in the process of learning to read, increases, and then subsequently decreases. Strings of identical letters delayed color naming for children just beginning to learn to read. The interference from words, presumably reflecting semantic processing, began developing early but did not peak until the second- to fourth-grade reading levels. These different sequences of development of interference in the various stimulus conditions suggest that word recognition is the result of a number of component processes that develop as children acquire skill in reading.     

The identification of names in maternal speech to infants

Mothers' speech to 14-month-old infants was recorded during a free-play session. The findings suggest that this speech contained a number of characteristics which could facilitate the identification of names from the other words in an utterance; names were frequently the loudest word of an utterance and were highly likely to be positioned at the end of utterances. Thus, infants appear to receive a verbal input which may help them to identify semantically important words.This research was supported by an S.S.R.C. grant to H. R. Schaffer, Dept. of Psychology, University of Strathclyde, Glasgow, Scotland.