Abstract
Purpose. In a transient attention task, Carrasco et al. (2004; Vision Research) found differences in response time (RT) and cue benefit depending on the position of the target. In a sustained attention task, Mackeben (1999; Spatial Vision) found differences in accuracy depending on position. The current study combines features of these two studies to determine if RTs also show this pattern in a sustained attention task. Methods. Three subjects identified the orientation of an E in a field of figure-8s presented in a circular array 7.5 deg from fixation. Subjects fixated a central dot for 1000 msec. Following this fixation period, a valid cue or no cue was presented for 1000 msec, followed by a delay of 100 or 1000 msec, then the target for 66 to 200 msec. Eye position was monitored with an Arrington Viewpoint® eyetracker. Trials on which the eyes moved more than ±1 deg were recycled. Cue and no cue conditions were blocked. In each block stimuli were presented 16 times at each position. Results. RTs were slower on the vertical meridian relative to the horizontal meridian (623±162 msec vs. 525±118 msec), and accuracy was reduced (67±15% vs. 93±9%). The data also show a greater cue benefit on the vertical meridian. The cue benefit for RT was 210±112 msec on the vertical meridian and 122±98 msec on the horizontal meridian. The cue benefit for accuracy was 21±16% on the vertical meridian and 6±12% on the horizontal meridian. Conclusions. The data show faster RTs and greater accuracy on the horizontal meridian in both cued and non-cued conditions. However, the effect of the cue was greater on the vertical meridian. These results replicate the differential performance fields found by Mackeben, and extend the RT asymmetries and cue benefits found by Carrasco et al. to a sustained attention task.