Hemispheric asymmetries for selective attention apparent only with increased task demands in healthy participants.

This study examined the possibility that lack of behavioral evidence indicating hemispheric specialization for selective attention in healthy individuals is due to the use of tasks that are not sufficiently demanding to require selective attention. In a group of 43 participants (ages 17-23), we compared selective attention on a cued-response time task when the target was presented alone and when a distractor was simultaneously presented. The costs of invalid cueing were minimal when the right hemisphere (RH) processed the target relative to when the left hemisphere (LH) processed the target, but only for the high load condition.

Triangular backgrounds shift line bisection performance in hemispatial neglect: the critical point.

Isosceles triangular backgrounds influence line bisection performance in normal control participants and patients with hemispatial neglect. When the triangles are oriented asymmetrically with the vertex in I visual field, and the base in the other, the perceived midpoint of horizontal lines within the triangle is shifted towards the base, and away from the vertex. The current study examines this illusion further by systematically varying the extent of the triangle presented.

Temporal discrimination learning in abstinent chronic alcoholics.

Background: Converging evidence from varied experimental paradigms has demonstrated that the cerebellum is involved in the timing of learned behavior. Given the documented neurological changes secondary to chronic alcoholism, particularly cerebellar degeneration, the ability of recovered chronic alcoholics to learn a temporal discrimination was assessed by using delayed eyeblink classical conditioning.

Methods: Twelve abstinent alcoholic participants and 12 matched control participants were randomly presented 2 clearly discriminable tone conditioned stimuli that were individually paired with 2 different interstimulus intervals.

Aware and unaware perception in hemispatial neglect: evidence from a stem completion priming task.

The current study used the process dissociation procedure in conjunction with a stem-completion priming task to disentangle the influences of aware and unaware perception in patients with hemispatial neglect. One lateralized picture prime was presented simultaneously with a filler picture followed by a centrally presented word stem. In the inclusion condition participants were asked to complete the word stem with the previously presented picture name; in the exclusion task they were asked to complete the stem with the name of a picture other than the one previously presented.