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RJ Watt

Publications and source records attributed to RJ Watt.

2 recordsLinked to original sources

The function of dynamic grouping in vision.

In this review we consider the logic and the evidence relating to the issue of dynamic grouping in human vision. Dynamic grouping is required when the visual system is creating novel descriptions, either because it is dealing with novel stimuli or it is providing information for novel purposes. In such cases, dynamic grouping provides a mechanism for discovering regularities in the data. We consider a number of examples, including grouping of visual information into surface descriptions and contour descriptions. The main issues that arise concern the configurability of the process and the effects of the propagation of local configurations. We then turn to the complex issue of visual search. Visual search allows the experimenter to establish something of the nature of pre-attentive visual descriptions and how these differ from attentive descriptions. We describe the basic results of visual search experiments in terms of the type of grouping involved. Finally, we consider the hypothesis that dynamic grouping is signalled by neuronal synchrony.

Journal Article↗

Do the eyes have it? Cues to the direction of social attention.

The face communicates an impressive amount of visual information. We use it to identify its owner, how they are feeling and to help us understand what they are saying. Models of face processing have considered how we extract such meaning from the face but have ignored another important signal - eye gaze. In this article we begin by reviewing evidence from recent neurophysiological studies that suggests that the eyes constitute a special stimulus in at least two senses. First, the structure of the eyes is such that it provides us with a particularly powerful signal to the direction of another person's gaze, and second, we may have evolved neural mechanisms devoted to gaze processing. As a result, gaze direction is analysed rapidly and automatically, and is able to trigger reflexive shifts of an observer's visual attention. However, understanding where another individual is directing their attention involves more than simply analysing their gaze direction. We go on to describe research with adult participants, children and non-human primates that suggests that other cues such as head orientation and pointing gestures make significant contributions to the computation of another's direction of attention.

Journal Article↗