The Joint Effects of Spatial Cueing and Transcranial Direct Current Stimulation on Visual Acuity

Abstract

The present study examined the mutual influence of cortical neuroenhancement and allocation of spatial attention on perception. Specifically, it explored the effects of transcranial Direct Current Stimulation (tDCS) on visual acuity measured with a Landolt gap task and attentional precues. The exogenous cues were used to draw attention either to the location of the target or away from it, generating significant performance benefits and costs. Anodal tDCS applied to posterior occipital area for 15 min improved performance during stimulation, reflecting heightened visual acuity. Reaction times were lower, and accuracy was higher in the tDCS group, compared to a sham control group. Additionally, in post-stimulation trials tDCS significantly interacted with the effect of precuing. Reaction times were lower in valid cued trials (benefit) and higher in invalid trials (cost) compared to neutrally cued trials, the effect which was pronounced stronger in tDCS group than in sham control group. The increase of cost and benefit effects in the tDCS group was of a similar magnitude, suggesting that anodal tDCS influenced the overall process of attention orienting. The observed interaction between the stimulation of the visual cortex and precueing indicates a magnification of attention modulation.

The Effect of Confidence Rating on a Primary Visual Task

“…Following the practice, in the test stage, all groups performed the cued Landolt gap task under identical standard conditions, i.e., no groups reported confidence, Figure 1. Results of the Standard Task group have been reported in Bonder et al (2018), this baseline group performance enabled to methodologically compare between the two lines of research.…”

“…Arguably, the process of task formation integrates task properties into a combined internal representation, thus enabling formalization of goal-directed strategies, tailored to that representation. Bonder et al (2018) have demonstrated the effect of task formation in the cued Landolt gap task where experimental manipulation exerted in practice caused prominent results in test.…”

“…Supplementing them, executive control manifests high cognitive involvement. Recently, Bonder et al (2018) examined whether involuntary visual attention in the cued Landolt gap task can be enhanced by external stimulation of the visual cortex. They applied transcranial Direct Current Stimulation (tDCS) for 15 min of initial practice, and found that in post-stimulation trials tDCS group showed significantly stronger attention orienting, compared to sham control.…”

“…Relying on the findings of Gopher et al (1989), Double and Birney (2017), and Bonder et al (2018), in the current study we aimed to inspect how confidence rating, introduced during the initial encounter with the task, will affect the post-practice performance. We hypothesized that integrating confidence rating even in a primary visual task such as the cued Landolt gap, will construct an internally enriched task formation, amplifying the effects of monitoring and control, and influencing performance as participants gain experience with the task.…”

Anodal transcranial direct current stimulation reduces collinear lateral inhibition in normal peripheral vision

“…When applied to the primary visual cortex, a-tDCS modulates contrast sensitivity 25,26 , visually evoked potential amplitude 25 and the visual cortex BOLD response 26 . Of particular importance for crowding, a-tDCS can immediately improve Vernier acuity and reduce surround suppression within the near-periphery [27][28][29] , possibly by modulating inhibition within the visual cortex. 27 Lateral masking, a well-established psychophysical paradigm for the assessment of low-level mechanisms that may contribute to crowding, involves the presentation of a central target Gabor patch between two flanker patches 12 .…”