No abstract

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.

It has been proposed that the unique need for early bilinguals to manage multiple languages while their executive control mechanisms are developing might result in long-term cognitive advantages on inhibitory control processes that generalize beyond the language domain. We review the empirical data from the literature on nonlinguistic interference tasks to assess the validity of this proposed bilingual inhibitory control advantage. Our review of these findings reveals that the bilingual advantage on conflict resolution, which by hypothesis is mediated by inhibitory control, is sporadic at best, and in some cases conspicuously absent. A robust finding from this review is that bilinguals typically outperform monolinguals on both compatible and incompatible trials, often by similar magnitudes. Together, these findings suggest that bilinguals do enjoy a more widespread cognitive advantage (a bilingual executive processing advantage) that is likely observable on a variety of cognitive assessment tools but that, somewhat ironically, is most often not apparent on traditional assays of nonlinguistic inhibitory control processes.

Using overt orienting, participants searched a complex visual scene for a camouflaged target (Waldo from the "Where's Waldo?™" books). After several saccades, we presented an uncamouflaged probe (black disk) while removing or maintaining the scene, and participants were required to locate this probe by foveating it. Inhibition of return was observed as a relative increase in the time required to locate these probes when they were in the general region of a previous fixation, but only when the search array remained present. Perhaps also reflecting inhibition of return, preprobe saccades showed a strong directional bias away from a previously fixated region. Together with recent studies that replicate the finding of inhibition at distractor locations following serial but not parallel visual search-so long as the search array remains visible-these data strongly support the proposal that inhibition of return functions to facilitate visual search by inhibiting orienting to previously examined locations.

Two visuospatial phenomena, serial search and inhibition of return, have recently gained the attention of scientists from such diverse disciplines as neuroscience, artificial intelligence and cognitive psychology. A linear increase in search latency with increasing display size has been assumed to reflect serial focused attention to each item in the display. A delay in the detection of a signal in a previously attended location has been assumed to reflect an inhibitory process that may be used to prevent attention from returning to the same stimulus. The following study of human performance supports these assumptions and, by demonstrating that inhibition of return operates in serial search, presumably to improve search efficiency, provides a functional link between these two phenomena.

In many situations, visual input tends to dominate other modalities in perceptual and memorial reports and in speeded responses. Visual dominance appears to be related to the relatively weak capacity of visual inputs to alert the organism to their occurrence. In response to this reduced alerting, subjects tend to keep their attention tuned to the visual modality. This bias works via prior entry to allow vision to control the mechanisms that subserve conscious reports. The study of visual dominance provides a model situation in which chronometric and phenomenological techniques can be brought together to produce a more complete picture of the relation between information processing and awareness. 157 AnnouncementThe Publications and Communications Board of the American Psychological Association announces the appointment of William K. Estes as editor of Psychological Re-view for the years

Inhibition of return (IOR) refers to slowed reaction times (RTs) when a target appears in the same rather than a different location as a preceding stimulus. The present study tested the hypothesis that IOR reflects a motor bias rather than a perceptual deficit. Two signals (S1 and S2) were presented on each trial. These signals were peripheral onsets or central arrows. The responses required to S1 and S2 were, respectively, no response-manual, manual-manual, saccadic-manual, no response-saccadic, manual-saccadic, and saccadic-saccadic. Uniting perceptual and motor bias views of IOR, the results demonstrated inhibition for responding to (a) peripheral signals when the eyes remained fixed (slowed visual processing) and (b) both peripheral and central signals when the eyes moved (slowed motor production). However, the results also emphasized that the nature of IOR depends fundamentally on the response modality used to reveal its influence.

Significant advances in cognitive neuroscience can be achieved by combining techniques used to measure behavior and brain activity with neural modeling. Here we apply this approach to the initiation of rapid eye movements (saccades), which are used to redirect the visual axis to targets of interest. It is well known that the superior colliculus (SC) in the midbrain plays a major role in generating saccadic eye movements, and physiological studies have provided important knowledge of the activity pattern of neurons in this structure. Based on the observation that the SC receives localized sensory (exogenous) and voluntary (endogenous) inputs, our model assumes that this information is integrated by dynamic competition across local collicular interactions. The model accounts well for the effects upon saccadic reaction time (SRT) due to removal of fixation, the presence of distractors, execution of pro- versus antisaccades, and variation in target probability, and suggests a possible mechanism for the generation of express saccades. In each of these cases, the activity patterns of "neurons" within the model closely resemble actual cell behavior in the intermediate layer of the SC. The interaction structure we employ is instrumental for producing a physiologically faithful model and results in new insights and hypotheses regarding the neural mechanisms underlying saccade initiation.