Noah Britt¹ (), Hong-jin Sun¹; ¹McMaster University

The distribution of attention across depth has recently attracted much research. Research from detection or localization tasks has suggested that attention is distributed more strongly toward near space than far space in the 3D environment. Such 'Near Advantage' has been demonstrated through faster reaction times in localizing near than far targets. However, when the task requires a discrimination response, the results for the depth effect were mixed in the literature. The current experiments sought to examine one potential moderating factor for the effect of depth: expectancy for the target configuration over trials. Recent research has led us to believe that whether participants can predict the task-prioritized target feature on a trial-to-trial basis may result in attention being allocated differently across depth. To investigate this question, using a simulated 3D environment, we implemented an orientation discrimination task where target stimuli were presented pseudorandomly at either the near or far depth plane and either left or right hemifield. In Experiment 1, the magnitude of the orientation differences were randomly selected from three values on every trial. In Experiment 2, the same three magnitudes of orientation differences were implemented between participants, with only one magnitude for a given participant; thus, participants could anticipate the magnitude of orientation difference in the upcoming trials. The results showed that when participants were unable to predict the configuration of the upcoming target stimuli, there was a null effect of depth (Experiment 1). However, when participants could form an expectation pertaining to the upcoming orientation differences, a far advantage was revealed (Experiment 2). These findings reveal that target expectancy could differentially impact attention distribution in a 3D discrimination task. The findings in this study could provide insights into learning in attentional allocation and the possible involvement of dorsal/ventral visual pathways in processing stimuli across 3D space.

Acknowledgements: NSERC, Canada Foundation for Innovation