Abstract
Visual orienting represents “the aligning of attention” with a stimulus (Posner, 1980). We examined the associations between multiple genetic markers (DBH, DRD4, DAT1, APOE e4, and COMT) and measures from a cued-orienting task. In previous research using this paradigm, costs have been combined with benefits into an overall validity score, and almost no genetic associations with visual orienting have been found (Fan, Wu, Fosella & Posner, 2001). It could be premature, however, to claim that genes play no role in explaining individual differences in orienting. If costs and benefits are determined by (even partially) distinct neural mechanisms, then they should be analyzed separately. This is consistent with Posner's formulation of orienting as a three-step process of disengaging, moving and then re-engaging attention at a new location. Disengaging attention (which is necessary for invalid but not for valid cues) could have separate genetic influences.
We used a modified cued-orienting paradigm (Posner, 1980) that added bilateral cues with unequal luminances (Kean & Lambert, 2003). Subjects respond with a left or right key press to the location of a small white square (the target) which appeared 150 msec after the brief presentation of a cue. The cue was either bright or dim. Subjects were told that the target had a 50% probability of appearing near the cue (for single cues) or near the brighter cue (for bilateral, asymmetric cues). Each individual's average response time (RT) to neutral cues served as a baseline for determining the costs and benefits of invalid and valid cues, respectively.
In our sample of 161 individuals, the correlation between costs and benefits was low, r = .25. Each of the genetic markers showed significant association with at least one attentional measure, especially with invalid dim cues. The majority of the genes showing associations with orienting code for dopamine.
Rice Graduate Student Research Fellowshipto RAL and Lynette S. Autrey Research grant to JLD.