Title:
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Attention capture by multiple events using dynamic displays
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Being able to select relevant visual information from among irrelevant information is critical for the successful accomplishment of many day to day activities. However, the locus of attentional selection is not always under the control of the observer. Certain events and stimuli in the visual environment have been shown to control selection against observers’ intentions and goals. These are said to capture attention in an automatic and stimulus driven manner. The events and stimuli that capture attention can be static (colour, shape, size, etc.) or dynamic (motion, flicker, etc.). This thesis examines the effect of dynamic stimuli on attentional selection by using a visual search paradigm. The findings suggest that neither motion per se nor the onset of motion captures attention. They also suggest that when low refresh rate motion is used, capture occurs, but this effect cannot be attributed to capture by motion onset (Chapter 3). Further, the second study suggests that attention capture is observed using low refresh rate motion onsets because they are not masked as compared with the static items in the display. Thus capture is put down to a relatively better visual quality and stimulus encoding rather than motion (Chapter 4). The findings from this thesis also suggests that when back and forth oscillatory motion is used, capture re-emerges, but this effect is best attributed to a change in direction that happens to be temporally unique (Chapter 5). Another important finding is that in attention capture by abrupt onset, only one onset is prioritised in search (Chapter 6). The findings overall argue for a strong role of low level factors in attention capture by dynamic stimuli.
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