Foveal target repetitions reduce crowding

Crowding is the limitation of peripheral vision by clutter. Objects that are easily identified when presented in isolation are hard to identify when presented flanked by similar close-by objects. It is often assumed that the signal of a crowded target is irretrievably lost because it is combined with the signals of the flankers. Here, we asked whether a target signal can be enhanced (or retrieved) by items presented far outside the crowding region. We investigated whether remote items matching a peripheral, crowded target enhanced discrimination compared to remote items not matching the target. In Experiment 1, we presented the remote item at different locations in the visual field and found that, when presented in the fovea, a matching remote item improved target discrimination compared to a nonmatching remote item. In Experiment 2, we varied stimulus onset asynchronies between target and remote items and found a strong effect when the remote item was presented simultaneously with the target. The effect diminished (or was absent) with increasing temporal separation. In Experiment 3, we asked whether semantic knowledge of a target was sufficient to improve target discrimination and found that this was not the case. We conclude that crowded target signals are not irretrievably lost. Rather, their accurate recognition is facilitated in the presence of remote items that match the target. We suggest that long-range grouping mechanisms underlie this "uncrowding" effect

Crowding, Attention and Consciousness: in support of the inference hypothesis

One of the most important topics in current work on consciousness is what relationship it has to attention. Recently, one of the focuses of this debate has been on the phenomenon of identity crowding. Ned Block has claimed that identity crowding involves consciously perceiving an object that we are unable to pay attention to. Others have offered different interpretations, emphasising the role of cognitive inference over conscious perception. In this paper, we draw upon a range of empirical findings to argue against Block’s interpretation of the data. We also argue that current empirical evidence strongly supports one particular version of the inference hypothesis . Finally, we consider the additional evidence Block gives in favour of his view, and argue that it fails to establish his position.Leverhulme Trust; Isaac Newton Trust; Royal Institute of Philosophy; Swiss National Science Foundation; FW

Perceptual grouping determines haptic contextual modulation

Since the early phenomenological demonstrations of Gestalt principles, one of the major challenges of Gestalt psychology has been to quantify these principles. Here, we show that contextual modulation, i.e. the influence of context on target perception, can be used as a tool to quantify perceptual grouping in the haptic domain, similar to the visual domain. We investigated the influence of target–flanker group- ing on performance in haptic vernier offset discrimination. We hypothesized that when, despite the apparent differences between vision and haptics, similar grouping principles are operational, a similar pattern of flanker interference would be observed in the haptic as in the visual domain. Participants dis- criminated the offset of a haptic vernier. The vernier was flanked by different flanker configurations: no flankers, single flanking lines, 10 flanking lines, rectangles and single perpendicular lines, varying the degree to which the vernier grouped with the flankers. Additionally, we used two different flanker widths (same width as and narrower than the target), again to vary target–flanker grouping. Our results show a clear effect of flankers: performance was much better when the vernier was presented alone compared to when it was presented with flankers. In the majority of flanker configurations, grouping between the tar- get and the flankers determined the strength of interference, similar to the visual domain. However, in the same width rectangular flanker condition we found aberrant results. We discuss the results of our study in light of similarities and differences between vision and haptics and the interaction between dif- ferent grouping principles. We conclude that in haptics, similar organization principles apply as in visual perception and argue that grouping and Gestalt are key organization principles not only of vision, but of the perceptual system in general

Grouping, pooling, and when bigger is better in visual crowding

In crowding, perception of a target is strongly deteriorated by nearby elements. Crowding is often explained by pooling models predicting that adding flankers increases crowding. In contrast, the centroid hypothesis proposes that adding flankers decreases crowding—‘‘bigger is better.’’ In foveal vision, we have recently shown that adding flankers can increase or decrease crowding depending on whether the target groups or ungroups from the flankers. We have further shown how configural effects, such as good and global Gestalt, determine crowding. Foveal and peripheral crowding do not always reveal the same characteristics. Here, we show that the very same grouping and Gestalt results of foveal vision are also found in the periphery. These results can neither be explained by simple pooling nor by centroid models. We discuss when bigger is better and how grouping might shape crowding