The temporal dynamics of visual crowding in letter recognition: Modulating crowding with alternating flicker presentations

Abstract

Visual crowding reduces the visibility of a peripherally presented group of stimuli. This is especially challenging for peripheral reading because adjacent letters or characters perceptually crowd one another. We investigated the temporal course of spatial visual crowding by sequentially alternating the visibility of the target and flanking letters within a trigram letter stimulus presented 9° below fixation. We found that alternation rates of roughly 3 Hz released half of the total effect of crowding, whereas 10 Hz alternation rates elicited near-crowded performance. Furthermore, we found a robust performance asymmetry whereby presenting the target first elicited better performance than presenting the flankers first, an effect resembling forward masking. These results held for conditions of high, medium, and low spatial crowding. Future work will determine whether the alternation rates found in the current study can improve peripheral reading.

Improving peripheral reading with non-invasive transcranial electrical stimulation of early visual areas

“…While between-letter and between-word crowding may negatively impact peripheral reading ability, color, contrast and spacing strategies for crowding reduction are ineffective at improving peripheral reading (Chung, 2002; Chung & Mansfield, 2009). Other studies have examined whether temporally separating the presentation of letters within a trigram or word improves overall letter or word recognition, again with limited success when using fast speeds relevant to reading (Haberthy & Yu, 2016; Silva et al, 2023).…”

“…To limit the impact of eye movements, sentences were presented on a computer screen using rapid serial visual presentation (RSVP) in which individual words were presented sequentially at specific presentation speeds and text sizes. A differential effect of tDCS was found whereby English readers exhibited a modest improvement after active tDCS but readers of Chinese exhibited no improvement (Silva et al, 2023).…”