Continuous attention: rationale and discriminant validation of a test designed for use in psychopharmacology

The continuous attention task (CAT) is a test designed to assess changes in attention due to a variety of factors, for example, drugs. Subjects view a series of 3x3 patterns of squares on a monitor screen, each displayed for 100 msec at intervals of 1.5–2.5 sec, and respond whenever two successive patterns are identical. For such a measure to be validr factors other than attention should be investigated, and shown not to be a factor in performance. Nineteen subjects took part in a study in which information-processing rate and recall of CAT figures was measured. The results showed that a viewing time of 50–60 msec was sufficient for 50% correct recognition of CAT figures, and that recognition with a masked presentation of 100 msec did not differ significantly from an unmaske presentation of 100 msec. Mean recall of CAT figures 2 sec after a 100-msec exposure was 98.2%. These results suggest that performance on the CAT is not limited by either information-processing speed or memory capacity, but is a valid measure of the ability to sustain attention.     

Reflections on human pavlovian decelerative heart-rate conditioning with negative tilt as US: Alternative approaches

The negative-tilt preparation that has been reported since the late seventies is a specific form of Pavlovian conditioning that is of scientific interest and has potential applications. In this paper I reflect on the usefulness, to the development of this preparation, of two approaches to Pavlovian conditioning. One approach is the older S-R learning, stimulus-substitution paradigm exemplified by learning texts of the sixties. The other is the modern, Tolman-like view, according to which the phenomenon of Pavlovian conditioning is “now described as the learning of relations among events so as to allow the organism to represent its environment.” The three assumptions encapsulated by this approach are: (a) that only CS-US contingency relations are learned; (b) that teleological modes of explanations are adequate; (c) that the representational theory of knowledge is sound. Concerning Pavlovian conditioning in general, questions been raised in the literature for all three assumptions; they have not been adequately answered. Regarding the specific problem of developing the human Pavlovian heart-ratedecelerative conditioning with negative tilt as the US, I suggest that the cognitive approach has been much less helpful than the older, S-R, stimulus-substitution paradigm. Nevertheless, other literature clearly indicates that the cognitive, S-S approach has generated considerable interest and research, especially in preparations like the conditioned emotional response (CER), which are CS-IR ones in the sense that the effects on the CR are assessed indirectly through measuring an indicator or instrumental response (IR). Finally, even in CS-CR preparations like human GSR conditioning, it is important to study the cognitive, S-S learning process through using such dependent variables as continuously assessed subjective CS-US contingency.     

Expert evidence by psychologists: Sometimes problematic and often premature

This article provides a critical review of two major types of expert evidence: (a) clinical assessments, and (b) generalizations drawn from psychological research. Strong arguments both for and against both types of testimony have been offered by legal experts and psychologists. These arguments are evaluated and the conclusion is drawn that there are two fundamental problems for psychologists in the role of expert. First, the types of assessments clinicians are asked to make (e.g., concerning the accused's mental state at the time of committing the offense) may exceed the capacity of the discipline; such assessments are problematic. Second, the research foundation that psychologists employ in court does not always apply to the court situation in the way experts imply; the application of laboratory research findings to real world contexts is sometimes premature. The article concludes with an admonition that psychologists should adopt a more conservative response to requests to provide expert evidence.