Temporal order judgments and presaccadic shifts of attention: What can prior entry teach us about the premotor theory?

A temporal order judgment (TOJ) 2-alternative forced choice design was used to examine presaccadic shifts of attention. Prior work on the premotor theory of attention (PTA) has predominantly focused on single-target discrimination tasks as a tool to measure accuracy and shifts of attention. It is important to demonstrate that the PTA is effective across attentional tasks that have been shown to be reliable in other contexts. Therefore, it was decided to use a perceptual task that probes multiple locations simultaneously and can equally be used to examine spatial spread of attention in more detail. In typical TOJ studies, prior entry is the metric used to measure an attentional effect. Prior entry is the biasing of temporal perception toward an attentionally cued location. This generally manifests as observers processing events at the cued location more rapidly, altering their perspective of temporal order. Participants were required to prepare saccades toward one of four targets, two of which would light up either synchronously or sequentially after a GO signal but before saccadic execution. Results demonstrated that in conditions with critical stimulus onset asynchronies, saccade preparation had a significant effect on performance. Prior entry effects were observed at saccade congruent locations with probes at these locations being typically perceived earlier than probes presented at a neutral location. These effects were not observed in control trials without a saccade. A further spatial effect was demonstrated for the attentional modulation, suggesting that this effect is restricted predominantly to horizontal configurations. Overall, results demonstrated that presaccadic attention is effective at eliciting a prior entry effect in TOJ designs and that such effects are more pronounced when the probes are distributed across the two lateral hemifields.