Abstract
Reaction time decreases during target selection if the target appears repeatedly in the same location. This phenomenon is known as priming, and is thought to occur because of a low-level memory of target location. Priming is also evident in anticipatory pursuit. Since both tasks have visual and motor components, it is not clear whether priming occurs in visual or motor pathways. In an attempt to determine this, we employ our go/nogo ocular baseball task in which trials either have visual and motor components, or visual components alone. Observers fixated a central point surrounded by a 4 deg circle (plate). A target moved at 10 deg/sec from the periphery toward the plate. Observers decided whether the target would intersect the plate (strike) or not (ball), and enforced their decision by pursuing the target for strikes, or maintaining fixation for balls. Strikes and balls were randomized. Errors occurred on ball trials preceded by strikes (43% errors), indicating that strikes caused priming. However, strikes preceded by balls were always accurate (0% errors), indicating balls did not prime. We next investigated whether cognitive expectation of rule state (strike or ball) on a given trial could override priming. To do this, the probability of rule state-reversal from trial to trial was varied from 0-100 %. At 0% reversal, rule state remained constant, enabling both cognitive expectation and priming. At 100% reversal, rule state reversed on every trial, enabling cognitive expectation, but opposing the priming effect. We found that strike trials were more subject to priming, but cognitive expectation had a greater effect on ball trials. The results suggest that priming occurs in the go circuitry of the pursuit system, while the nogo circuitry is more susceptible to cognitive influence.
Meeting abstract presented at VSS 2013