Temporal Crowding With Central Vision Reveals the Fragility of Visual Representations

This study examined whether temporal crowding-the impaired object identification when distracting objects precede and succeed it-occurs at the fovea and if so whether its magnitude is reduced. We presented a central sequence of three oriented items separated by relatively long intervals (200/400 ms) and used an orientation estimation task with mixture-model analyses. We found clear evidence of temporal crowding with central vision, even with 400 ms intervals. Critically, reduced encoding precision surfaced as a robust and unique characteristic of temporal crowding. The magnitude of central and peripheral temporal crowding was similar suggesting the involvement of higher visual areas. Precision impairment emerged even when only the target contained orientation information, excluding "response competition" as the sole interference mechanism; yet it was larger when all items included orientation information, underscoring the importance of orientation-selective mechanisms. Overall, we show that even with central simple stimuli, the formation of a stable visual representation is surprisingly slow. Public Significance StatementOur study qualifies the common view that the visual system generates internal representations of visual objects very fast. We show that the internal representation of a simple oriented line is less precise when other orientated lines precede and succeed it, even when these stimuli are separated by long intervals and presented to the center of the visual field, where visual information is processed with the highest acuity. This suggests that generating a stable visual representation requires a surprisingly long time. Importantly, the finding that a similar interference emerges across the visual field suggests that the mechanisms underlying this long-lasting temporal interference involve processes taking place at later, higher visual areas. Additionally, this study elaborates on the conditions under which this long-lasting temporal interference may occur, thereby helping those who wish to avoid it.