Attention capture by multiple events using dynamic displays
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.