Christa-Lynn Donovan | Search PubMed

PubMed2004

Flexible and abstract resolutions to crossmodal conflicts.

Participants judged whether two sequential visual events were presented for the same length of time or for different lengths of time, while ignoring two irrelevant sequential sounds. Sounds could be either the same or different in terms of their duration or their pitch. When the visual stimuli were in conflict with the sound stimuli (e.g., visual events were the same, but the sounds were different) performance declined. This was true whether sounds varied in duration or in pitch. The influence of sounds was eliminated when visual duration discriminations were made easier. Together these results demonstrate that resolutions to crossmodal conflicts are flexible across the neural and cognitive architectures. More importantly, they suggest that interactions between modalities can span to abstract levels of same/different representations.

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PubMed2004

Hemispheric performance in object-based attention.

The goal of the present study was to investigate whether object-based attention effects differ across the cerebral hemispheres. Previous research has suggested that object-based attention is preferentially lateralized to the left hemisphere (Egly, Driver, & Rafal, 1994; Egly, Rafal, Driver, & Starrveveld, 1994). However, work by Vecera (1994) has suggested that these previous studies may have failed to obtain a pure measure of object-based attention. The present study applied modified versions of Duncan's (1984) seminal object-based attention paradigm. Subjects were typically presented with one target object to a single visual field (one-object display), two target objects to the same visual field (two-object unilateral display), or two target objects to different visual fields (two-object bilateral display). In all three experiments, response accuracy was higher for the one-object displays than for the two-object displays. Most important, this object-based cost was especially severe when selection of two target elements was isolated to the right visual field (left hemisphere). We confirmed that this effect was specific to object-based attention in three different ways: Experiment 1 manipulated stimulus distance, as recommended by Vecera; Experiment 2 ensured that target selection was based on nonspatial attributes; and Experiment 3 used overlapping displays, as in Duncan (1984). Collectively, the data are in accord with previous conclusions that object-based attention is a specialized form of orienting subserved by lateralized cortical brain mechanisms. However, contrary to previous research, it appears that it is the right hemisphere, and not the left hemisphere, that is preferentially biased for committing object-based attention to elements in the visual environment.

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