The roles of feature-specific task set and bottom-up salience in attentional capture: An ERP study.

We investigated the roles of top-down task set and bottom-up stimulus salience for feature-specific attentional capture. Spatially nonpredictive cues preceded search arrays that included a color-defined target. For target-color singleton cues, behavioral spatial cueing effects were accompanied by cue-induced N2pc components, indicative of attentional capture. These effects were only minimally attenuated for nonsingleton target-color cues, underlining the dominance of top-down task set over salience in attentional capture. Nontarget-color singleton cues triggered no N2pc, but instead an anterior N2 component indicative of top-down inhibition. In Experiment 2, inverted behavioral cueing effects of these cues were accompanied by a delayed N2pc to targets at cued locations, suggesting that perceptually salient but task-irrelevant visual events trigger location-specific inhibition mechanisms that can delay subsequent target selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simon effect with and without awareness of the accessory stimulus.

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or ≥200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional asymmetry in schizophrenia: Disengagement and inhibition of return deficits.

This research examined 2 components of visual orienting in medicated schizophrenia patients: the validity effect and the inhibition of return (IOR). In the 1st experiment, patients showed the expected asymmetry in orienting attention, that is, larger validity effect in the right visual field than in the left. However, this asymmetry was due to a deficit in facilitatory processes rather than a disengagement deficit. In addition, patients showed a deficit in IOR. In the 2nd experiment, a 2nd central cue for summoning attention, explicitly, back to the center was used. In this experiment, normal IOR in schizophrenia patients was found. Because it was shown that schizophrenia patients do not have a disengagement deficit, IOR possibly could not be observed because of the increased facilitation in that location. It was proposed that the abnormality in visual attention in schizophrenia is due to a deficit in inhibitory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interference effects by spatial proximity and age-related declines in spatial memory by Japanese monkeys (Macaca fuscata): Deficits in the combined use of multiple spatial cues.

Spatial information processing was assessed in 3 young (4-10 years old) and 4 aged (24-25 years old) Japanese monkeys (Macaca fuscata) on 3 delayed nonmatching-to-position (DNMP) tests with relatively short delays of 5 s. Each test had 3 conditions of different horizontal distances between sample and to-be-nonmatched positions. Experiment 1 demonstrated that the performance on the DNMP test in both age groups was impaired when 2 stimulus positions were located next to each other; however, it was fairly accurate when they were located farther apart, suggesting that interference is introduced by spatial proximity. Experiment 2 revealed age-related differences in the situation in which an additional spatial cue, depth information, was available by extending the stimulus array of the DNMP test to a 4 = 2 matrix. In this test, young monkeys performed accurately irrespective of position distance between stimuli, whereas the aged monkeys' performance remained the same as before. Experiment 3 confirmed that the recognition ability in aged monkeys was well preserved on DNMP tests with different objects. These patterns of results indicate that the ability to use information from multiple spatial cues is not accessible to the aged monkeys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)