Task-Switching Effects for Visual and Auditory Pro- and Antisaccades: Evidence for a Task-Set Inertia

Abstract

ABSTRACT. The completion of an antisaccade delays the reaction time (RT) of a subsequent prosaccade; however, the converse switch does not influence RT. In accounting for this result, the task-set inertia hypothesis contends that antisaccades engender a persistent nonstandard task-set that delays the planning of a subsequent prosaccade. In contrast, the coordinate system transformation hypothesis asserts that the transformation required to construct a mirror-symmetrical target representation persistently inhibits prosaccade planning. The authors tested the latter hypothesis by examining switch-costs for pro- and antisaccades directed to visual (i.e., the stimuli used in previous work) and auditory targets. Notably, auditory cues are specified in a head-centered frame of reference prior to their conversion into the retinocentric coordinates necessary for saccade output. Thus, if the coordinate system transformation hypothesis is correct then auditory pro- and antisaccades should elicit a bidirectional switch-cost because each requires a coordinate transformation. RTs for visual and auditory modalities showed a reliable—and equivalent magnitude—prosaccade switch-cost. Moreover, performance (e.g., movement time) and kinematic (e.g., velocity) variables indicated the switch-cost was restricted to response planning. As such, results are incompatible with the coordinate system transformation hypothesis and therefore provide convergent evidence that a task-set inertia contributes to the prosaccade switch-cost.

Keywords:

• antisaccade
• auditory
• oculomotor
• prosaccade
• task-switch

Notes

1. Four simple-effects contrasts were used to decompose the modality by task by target eccentricity interactions (i.e., for PV and amplitude). As per the described in the Method section, contrasts involving three or more means were evaluated with an adjusted p value (i.e., p = .0125).

2. The classic view of the lateral PFC asserts its role in suppressing an unwanted response by inhibiting activity in the oculomotor system. Notably, however, Johnston, Koval, Lomber, and Everling (2014) recorded single-cell activity in the SC during unilateral cryogenic deactivation of the PFC and showed the latter's excitatory role related to the maintenance of an appropriate oculomotor task-set (for a review, see Everling & Johnston, 2013).

Additional information

Funding

Supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada and Faculty Scholar and Major Academic Development Fund Awards from the University of Western Ontario.