Speed-accuracy tradeoff in double stimulation: Effects on the first response

A single-stimulation and two double-stimulation response conditions were compared using explicit payoff matrices to vary speed-accuracy tradeoff. Under accuracy payoff, response latency (RT(1)) to the first stimulus increased as ISI dropped but accuracy remained high and relatively constant. Under speed payoff, RT(1) was only slightly affected by ISI but accuracy dropped as ISI decreased. Transmitted information rates consistently reflected detrimental effects of short ISI. In double stimulation, but not in single stimulation, error response latency exceeded correct response latency. Furthermore, error response latencies were found to be far more variable and more sensitive to changes in speed-accuracy condition than were correct response latencies. Finally, under both speed and accuracy conditions, response latency to the first of two successive stimuli was faster if a response was also required to the second stimulus. Implications of the data for possible models of double-stimulation speed-accuracy tradeoff are considered.     

The response criterion,the stimulus configuration,and the relationship between brightness contrast and brightness constancy

Four experiments were designed to investigate the nature of the relationship between brightness contrast and brightness constancy while controlling the response criterion, the area of the surround, the stimulus configuration, and the mode of appearance of the modulus target. Ten Os in each of the four experiments estimated the apparent whiteness or brightness of targets with different contrast ratios. All targets were viewed at several illumination levels. Most constancy (whiteness and brightness) functions displayed shallow slopes that reflected a good approximation to constancy. The functions within Experiments I, III, and IV were vertically displaced and parallel; those in Experiment II were vertically displaced and increased in slope. This suggests that decreasing the contrast ratio had no effect on the tendency towards constancy when the area of the surround was greater than that of the target but resulted in a decrease in constancy when the area of the surround was equal to that of the target.     

Time discrimination training of laboratory animals using a PDP-8 computer

The purpose of this paper Is to describe the use of a small, general-purpose digital computer system in the training of laboratory animals to discriminate stimuli on the basis of their duration. The computer hardware and software required for such training, together with some illustrative results from two recent studies, will be described.     

Closed- and open-class lexical access in agrammatic and fluent aphasics

Bradley, Garrett, and Zurif (Bradley, Computational distinctions of vocabulary type. Unpublished doctoral dissertation, MIT Press; Cambridge, MA, 1978; Biological studies of mental processes, MIT Press, Cambridge, MA, 1980) have suggested that closed-class word access is normally mediated by a different route than the open-class one, and that the loss of this closed-class route might account for agrammatism. However, in an earlier study ( Gordon & Caramazza, Brain and Language, 15, 143–160, 1982) we were not able to confirm a meaningful difference between closed- and open-class word frequency responsiveness of the type Bradley (unpublished dissertation, 1978) had seemed to find in normal subjects. We have now done a direct comparison of closed-class frequency sensitivity in agrammatic and nonagrammatic aphasics, to directly test Bradley and colleagues' hypotheses and to avoid some of the experimental problems with between-class frequency comparisons. We find that closed-class words behave similarly whether or not the subject is agrammatic. Therefore, the differences between agrammatic and nonagrammatic aphasics must arise at a deeper level (or levels) of lexical processing than the one probed by the frequency sensitivity effect.     

Alternative Living Arrangements for Older Persons

Billings, G. Alternatives to Nursing Home Care: An Update. Aging, 1982, Nos. 325–326, 2–11. Brill, R.S. New York City Home Care Project: A Coordinated Health and Social Service Approach. Aging, 1982, Nos. 325–326, 12–15. Gray, P.J. State Experiences with Long-term Care. Aging, 1982, Nos. 325–326, 28–33. Sager, A. Improving the Provision of Long-term Care. Aging, 1982, Nos. 325–326; 16–27.     

Extraversion and electrodermal activity: arousability and the inverted-U

The Eysenck hypothesis that extraverts are less aroused or more inhibited than introverts has been subjected to a number of tests in the psychophysiological literature. Research to date suggests the need to clearly differentiate between tests of overall group differences in arousal or inhibition and studies of the differential reactions of the two groups to arousal manipulations. Psychophysiological studies of overall arousal differences in our laboratories and elsewhere have yielded somewhat inconsistent results for SCL, nonspecific response frequency, trials-to-criterion habituation and initial response amplitude, though dishabituation results are consistent with the expectation of higher amplitudes in introverts. Far more consistent are findings testing the inverted-U hypothesis, which suggests that introverts reach a point of optimal arousal at lower levels of stimulus input than do extraverts and hence should show earlier asymptotes and decrements in arousal measures. Using stimulus intensity and caffeine to manipulate arousal, we have found supportive results for SCL and several phasic measures, including the initial, test, and dishabituation responses. Overall, findings suggest that the two personality groups differ more clearly in arousability than in overall arousal level and that this difference is most consistent when conditions induce a rapid breakdown of inhibition and increase in arousal. Further research is needed to better understand the conditional relationship of extraversion to arousability, and arousal-manipulation paradigms would appear to be a fruitful initial approach to carrying out the needed research.     

Hemispheric differences in picture-word interference

In a picture-word version of the Stroop task, 30 right-handed subjects were tested under each of six conditions in which a picture alone or a picture plus a word were presented to the left, the right, or both hemispheres. In two additional conditions the picture was presented to the right hemisphere and the word was simultaneously presented to the left hemisphere, or vice versa. For all conditions, subjects were instructed to name the picture only, as rapidly as possible. Picture naming times were significantly slower for the conditions in which the pictures were accompanied by words than in the respective picture alone conditions. Moreover, simultaneous presentation of a picture and a word to both hemispheres resulted in greater interference (slower picture naming times) than did the simultaneous presentation of the picture and the word to either the left hemisphere alone or the right hemisphere alone. The latter two conditions, in turn, resulted in significantly more interference than did the simultaneous presentation of the picture to one hemisphere and the word to the other hemisphere. This pattern of results suggests that the Stroop effect obtained under normal circumstances is in large part a function of the interference caused by the simultaneous processing of items in the same hemisphere. In contrast to hemispheric differences reported for the color-word Stroop task, the effect of presenting a picture and word simultaneously to the right hemisphere did not differ reliably from that of presenting a picture and word to the left hemisphere. The failure to replicate this aspect of the color-word Stroop is attributed to differences in the abilities of the two hemispheres to process the respective target items (the color or the picture) of the two tasks.     

Convergent and concurrent validation of four measures of assertion

This study examined the relationship among the College Self-Expression Scale (CSES), the Dominance Scale of the California Psychological Inventory (Do), role-play assessment, and peer ratings of assertion. Peer ratings served as the criterion measure. Fifty-three members of a college sorority completed the CSES and the Do Scale, role played eight scenes requiring an assertive response, and rated each other on a five-point scale of assertion. Peer ratings were significantly correlated with the Do Scale and the CSES. A significant correlation was also obtained between the CSES and the Do. Role-play ratings were not significantly related to any measure. Results are discussed in terms of convergent and concurrent validity for the Do and CSES as measures of assertion. A precautionary note is presented regarding the use of role-play assessment for measuring assertion and as a behavioral validation procedure.     

The perception of distance and location for dual tactile pressures

The concept that distance on the skin is frequently misperceived was first reported over a century ago by Weber. Weber and others have reported that the apparent distance between pressure stimuli fluctuates with both body site and stimulus orientation. The present study confirms these effects and shows that the misperceptions are usually compressive in nature. It further establishes that errors in perceived distance correspond to errors in perceived location, indicating that an interaction exists between the perceptual processes responsible for percepts of tactile location and distance. Perceived location depends on the relationship of a tactile stimulus both to the body frame and to nearby stimuli, and the effect of nearby stimuli is to induce a perceptual affinity between sensations of pressure. These results are discussed in relation to the more frequently examined dynamic illusions of tactile distance (tau phenomenon) and location (the cutaneous rabbit).     

An evaluation of reality orientation therapy

An evaluation was made of reality orientation therapy utilizing 14 male patients with dementias of various types. The therapy is designed to improve memory and reduce confusion in elderly and demented individuals. Utilizing a group comparison with crossover design, it was found that the patients improved significantly over sessions on orientation items actually taught during those sessions. However, no significant improvement was found on a series of generalization items consisting of orientation-related questions that were not asked during sessions. Furthermore, there was no generalization to ward activities. It was noted that individual responses to the treatment were quite varied, and so three cases reflecting highly different responses are presented.Indebtedness is expressed to the Veterans Administration for support of this research.