Abstract
Crowding refers to impaired object identification when presented with other objects. A common explanation for spatial crowding – crowding from adjacent objects – suggests that it reflects an excessive information integration across space (e.g., pooling or averaging of the target and its flankers). Recently we have shown that crowding can also occur across time (i.e., when the target is preceded and/or succeeded by other irrelevant stimuli), with inter-items intervals that are longer than the limits of ordinary masking (SOA range: 170-475ms). In a series of experiments, we used an orientation estimation task in which participants were presented with a sequence of three oriented stimuli. The target was the second stimulus, and the task was to reproduce its orientation. Estimation errors were analyzed using a mixture-model analysis. Such analyses revealed that temporal crowding affects the precision of target encoding and the rate of substitution errors, but it does not affect the guessing rate. Also, temporal crowding occurs at the fovea; and it is a unique phenomenon that is different from ordinary masking. The goal of the current study was to examine whether temporal crowding also reflects pooling/averaging of information across time. To that end, we asked our participants to estimate the average orientation of all items rather than the orientation of the target. Though it seems that our participants were able to report the average stimuli orientation, the pattern of SOA effects on encoding precision, guessing rate, and substitution errors that emerged for this ‘average estimation task’ was very different from the pattern observed for estimating the target’s orientation. Specifically, for the averaging task, the only significant SOA effect found was for the substitution rate. Substitution errors decreased as the SOA increased. These different patterns of results suggest that temporal crowding is not mediated by averaging across time.