Biomedical subjects

Raymond M Klein

Publications and source records attributed to Raymond M Klein.

25 records · Page 2Linked to original sources

PubMed2002

Contribution of the primate superior colliculus to inhibition of return.

The phenomenon of inhibition of return (IOR) has generated considerable interest in cognitive neuroscience because of its putative functional role in visual search, that of placing inhibitory tags on objects that have been recently inspected so as to direct further search to novel items. Many behavioral parameters of this phenomenon have been clearly delineated, and based on indirect but converging evidence, the widely held consensus is that the midbrain superior colliculus (SC) is involved in the generation of IOR. We had previously trained monkeys on a saccadic IOR task and showed that they displayed IOR in a manner similar to that observed in humans. Here we recorded the activity of single neurons in the superficial and intermediate layers of the SC while the monkeys performed this IOR task. We found that when the target was presented at a previously cued location, the stimulus-related response was attenuated and the magnitude of this response was correlated with subsequent saccadic reaction times. Surprisingly, this observed attenuation of activity during IOR was not caused by active inhibition of these neurons because (a) they were, in fact, more active following the presentation of the cue in their response field, and (b) when we repeated the same experiment while using the saccadic response time induced by electrical micro-stimulation of the SC to judge the level of excitability of the SC circuitry during the IOR task, we found faster saccades were elicited from the cued location. Our findings demonstrate that the primate SC participates in the expression of IOR; however, the SC is not the site of the inhibition. Instead, the reduced activity in the SC reflects a signal reduction that has taken place upstream.

Action Potentials↗

PubMed2002

Temporal dynamics of reflexive attention shifts: a dual-stream rapid serial visual presentation exploration.

We combined a prototypical exogenous cuing procedure with rapid serial visual presentation (RSVP) to provide a precise characterization of the temporal dynamics of reflexive attention shifts. The novel paradigm thus created has several useful properties, most notably that the physical presentation of the target is neither an onset nor a unique event and that temporal precision is provided without the requirement for a speeded response. A biphasic pattern was observed, with early benefits followed by later costs (inhibition of return) at the cued location relative to the uncued location. The finding of inhibition of return in this paradigm disproves the assertion that inhibition of return is merely a reluctance to respond in the target's direction. It may be partly that, but encoding mechanisms linked to attention must also be involved.

Adult↗

PubMed2002

Eliminating the cost of task set reconfiguration.

With insufficient time to fully prepare for a switch in task, a deterioration in performance on the first trial of a new task would be expected. The interest of researchers has been captured by the residual switch costs that, surprisingly, remain despite sufficient time to prepare. We used avery simple task to investigate the costs to reaction time and accuracy associated with changing between two different instructional sets every eight trials. Subjects responded to left and right visual targets by making either spatially compatible or incompatible eye movements (Experiment 1) or buttonpress responses (Experiment 2). The subjects were cued as to whether to make the compatible or the incompatible response by the color of a border appearing on the perimeter of the display. In cases in which the subject alternated between making pro- and antisaccades, the large costs to reaction time and accuracy at the short cue-target stimulus onset asynchrony were completely eliminated when sufficient time was provided to prepare for the switch. This complete elimination of residual switch costs was not obtained when the same alternation was applied to manual responses. This pattern of results links residual costs to response selection processes and suggests that they are not a necessary component of the switch process. We propose that the elimination of "stubborn" residual switch costs is rooted in our use of a hypercompatible task (making saccades toward targets) that places minimal demands on response selection.

Form Perception↗

PubMed2002

Does attention follow the motion in the "shooting line" illusion?

When a line is presented in the vicinity of a recent luminance change (peripheral cue), it is perceived to be drawn over time away from its "cued" end even though the line is actually presented all at once. This study was designed to determine whether attention, exogenously attracted to the cue, would come under the exogenous control of this illusory motion and follow the drawing motion from the cued end to its terminus. Each trial began with the display of four small squares at the corners of an imaginary square centered about fixation. On the critical trials, one of the four squares brightened briefly, after which a horizontal line was presented joining either the two upper or the two lower squares. Shortly thereafter, the distribution of attention was determined by asking the observer to indicate the nature of a change that was equally likely to occur to one of the squares. Responses to targets presented at a noncued location that was at the end of an illusorily drawn line were as fast as those to targets at the cued location and were much faster than those to targets at the remaining noncued locations. This pattern was not shown when the line preceded the cue, strongly suggesting that attention follows the motion in this illusion.

Adolescent↗

PubMed2002

Inhibition of return interacts with the Simon effect: an omnibus analysis and its implications.

Previous research has reported that the Simon effect (a type of stimulus-response [S-R] compatibility effect) and the inhibition of return effect (IOR; a late cuing effect) do not interact. In this brief report, we analyzed published and unpublished experiments that have examined these effects and found that IOR actually increases the Simon effect. This is a remarkable finding because most factors that delay reaction times (as IOR does) actually decrease the Simon effect. We examine this interaction within the context of seven interpretations of the effect that IOR may have on the task-irrelevant S-R code and two interpretations of the effect that IOR may have on the task-relevant S-R code, two components that underlie the Simon effect. The results falsified more than half of these interpretations, thus permitting future investigations to further reduce the number of theoretical alternatives.

Attention↗

PubMedDate not supplied

Modelling divided visual attention with a winner-take-all network.

Experimental evidence on the distribution of visual attention supports the idea of a spatial saliency map, whereby bottom-up and top-down influences on attention are integrated by a winner-take-all mechanism. We implement this map with a continuous attractor neural network, and test the ability of our model to explain experimental evidence on the distribution of spatial attention. The majority of evidence supports the view that attention is unitary, but recent experiments provide evidence for split attentional foci. We simulate two such experiments. Our results suggest that the ability to divide attention depends on sustained endogenous signals from short term memory to the saliency map, stressing the interplay between working memory mechanisms and attention.

Algorithms↗

PubMedDate not supplied

A laboratory-based investigation of relations among video lottery terminal (VLT) play, negative mood, and alcohol consumption in regular VLT players.

Thirty regular video lottery terminal (VLT) players were randomly assigned to 90 min of VLT play or a control activity (viewing a movie) to examine the impact of VLT play on alcohol use. Ratings of dysphoric mood were taken at baseline, midactivity, and postactivity. Alcoholic and nonalcoholic control beverages were available throughout. As hypothesized, those in the VLT condition were more likely to consume alcoholic than nonalcoholic control beverages (i.e., 73% drank alcohol and 20% drank control beverages), whereas no such preference for alcohol was observed in the movie control condition (i.e., 40% drank alcohol and 47% drank control beverages). Consistentwith predictions derived from Steele and Josephs' [J. Abnorm. Psychol. 97 (1988) 196; Am. Psychol. 45 (1990) 921.] attention allocation model, VLT condition participants who drank alcohol showed increases in dysphoric effect over the course of testing. No such changes in negative mood were observed in VLT participants who did not consume alcohol or in movie control participants regardless of whether they drank alcohol. An observed temporal pattern of greater drinking during the early phase of VLT play indicated that the relation between alcohol use and dysphoric affect among VLT condition participants could not readily be explained by drinking to relieve dysphoria induced by VLT losses. Clinical and policy implications are discussed.

Adult↗