Shared attention for action selection and action monitoring in goal-directed reaching

Abstract

Dual-task studies have shown higher sensitivity for stimuli presented at the targets of upcoming actions. We examined whether attention is directed to action targets for the purpose of action selection, or if attention is directed to these locations because they are expected to provide feedback about movement outcomes. In our experiment, endpoint accuracy feedback was spatially separated from the action targets to determine whether attention would be allocated to (a) the action targets, (b) the expected source of feedback, or (c) to both locations. Participants reached towards a location indicated by an arrow while identifying a discrimination target that could appear in any one of eight possible locations. Discrimination target accuracy was used as a measure of attention allocation. Participants were unable to see their hand during reaching and were provided with a small monetary reward for each accurate movement. Discrimination target accuracy was best at action targets but was also enhanced at the spatially separated feedback locations. Separating feedback from the reaching targets did not diminish discrimination accuracy at the movement targets but did result in delayed movement initiation and reduced reaching accuracy, relative to when feedback was presented at the reaching target. The results suggest attention is required for both action planning and monitoring movement outcomes. Dividing attention between these functions negatively impacts action performance.

Probing the deployment of peripheral visual attention during obstacle-crossing planning

“…Moreover, during stationary trials, visual performance did not differ across the four locations, suggesting that the brain placed equal priority on information processing at all locations relevant to the task. This interpretation is also supported by a recent reaching study that showed that letter discrimination is enhanced at both reaching and non-reaching locations with movement-relevant feedback (Mahon et al, 2020).…”

“…Reaching studies have shown that preparing a reach results in enhanced visual performance at the movement location at short cue-test intervals (~100 ms; Baldauf et al, 2006 ; Baldauf, 2011 ; Rolfs et al, 2013 ; Stewart et al, 2019 ; Mahon et al, 2020 ), followed by a decrease in performance at the movement location at longer cue-test intervals (>250–300 ms; Deubel and Schneider, 2003 ; Stewart et al, 2019 ). For this first iteration of the protocol, we tested visual performance and sensitivity using a relatively long cue-test interval of 300 ms. At such longer cue-test intervals, we anticipated a reduction in visual performance and sensitivity to movement-relevant locations, indicating a re-direction of attention and implying that movement planning is complete, as per the concept of inhibition of return—once the cued location is sufficiently processed, attention is inhibited at the cued location and re-directed to other “novel” task-relevant (uncued) locations (Posner, 1980 ; Posner and Cohen, 1984 ; Posner et al, 1985 ).…”

“…For this first iteration of the protocol, we tested visual performance and sensitivity using a relatively long cue-test interval of 300 ms. At such longer cue-test intervals, we anticipated a reduction in visual performance and sensitivity to movement-relevant locations, indicating a re-direction of attention and implying that movement planning is complete, as per the concept of inhibition of return—once the cued location is sufficiently processed, attention is inhibited at the cued location and re-directed to other “novel” task-relevant (uncued) locations (Posner, 1980 ; Posner and Cohen, 1984 ; Posner et al, 1985 ). Thus, based on reaching studies (Deubel and Schneider, 2003 ; Baldauf et al, 2006 ; Baldauf, 2011 ; Rolfs et al, 2013 ; Stewart et al, 2019 ; Mahon et al, 2020 ), we could assume that planning the first step led to a transient and reflexive enhancement of attention to the first stepping location, followed by the inhibition of attention at this location once it was processed and the movement plan for the first step formed. Future studies using this protocol with shorter cue-test intervals would be required to investigate whether the time course of modulation of visual attention during skilled walking generalizes from that expected from our understanding of the control of upper limb tasks.…”

“…To navigate everyday environments, the brain must deploy visual attention to relevant sensory stimuli to assist in formulating a movement plan and executing the desired action based on movement goals (Fecteau and Munoz, 2006 ; Gottlieb, 2007 ; Bisley and Goldberg, 2010 ). The allocation of visual attention can occur transiently (reflexively) in response to a sudden stimulus (Nakayama and Mackeben, 1989 ; Ling and Carrasco, 2006 ; Grubb et al, 2015 ) or in preparation for a movement (Baldauf et al, 2006 ; Rolfs and Carrasco, 2012 ; Rolfs et al, 2013 ; Stewart et al, 2019 ; Mahon et al, 2020 ), or it can be sustained (voluntary) based on behavioral objectives (Nakayama and Mackeben, 1989 ; Deubel and Schneider, 2003 ; Ling and Carrasco, 2006 ; Grubb et al, 2015 ). Numerous studies on the execution of skilled walking (e.g., obstacle crossing) in animals (Drew and Marigold, 2015 ) and humans (Patla, 1998 ; Niang and McFadyen, 2004 ; Marigold, 2008 ) have shed light on the role of central vision in the control of skilled walking.…”

“…Reaching studies demonstrate a strong coupling between movement planning and covert selective attention. For example, preparing a reach enhances visual discrimination (Baldauf et al, 2006 ; Baldauf, 2011 ; Rolfs et al, 2013 ; Mahon et al, 2020 ) at covertly (peripherally) attended reach locations compared to non-reach locations. These enhancements in visual performance (percentage of correct responses) and visual sensitivity ( d’ ) at the upcoming reach location occur when the test stimulus appears ~50–100 ms after the onset of the movement cue.…”