Aging and mechanisms of visual selective attention : effects on word localization and identification

The present study investigated age differences in attentional allocation in a word localization and identification task. Response times for valid and invalid spatial cue conditions were compared for each of two age groups under two SOA conditions: 500 msec and 1000 msec. Very high benefits for valid cues in terms of response time were found for both groups. Results indicated that attention was more important for words when compared with similar earlier studies using a simple shape identification task. A sensitive model-fitting technique was used to compare the cost and benefit of selective attention to words; it revealed that attention can be concentrated away from the fovea to benefit in word identification in much the same way for both age groups. The model-fit analysis also revealed that attention for word identification, and perhaps any more complex visual stimuli, is more diffuse than for simple shape identification. In addition, older adults are more likely to avoid the foveal area in order to distribute attentional resources to the periphery and are able to increase these effects of selection at the longer SOA. This suggests that older adults are using attention to offset visual processing deficits for peripheral information such as letter information in the reading process. The results support a two-process view of attention where attention consists both of selection and inhibition and provide evidence to support a theory of reduced inhibitory processes as a cause for cognitive slowing associated with aging