Visual attention has been compared to a spotlight with an adjustable beam
and to a zoom lens. However, although such analogies are intuitively appeal-
ing, there appears to be more processing of unattended visual stimuli outside
the attentional beam than would be expected. It is also the case that visual
attention operates in a more flexible fashion than is implied by the zoom-lens
model.
Research by cognitive neuropsychologists has indicated that the attentional
system is not unitary. Attention appears to involve at least three different pro-
cesses (i.e. disengagement of attention from one stimulus; shifting of attention;
engagement of attention on to a new stimulus), and brain damage sometimes
selectively affects one or other of these processes.
Studies of divided attention involve presenting subjects with two tasks at the
same time, with instructions to perform both tasks as well as possible. At an
empirical level, the main issue is to identify those factors determining whether
two tasks can be performed successfully at the same time. Three of the main
factors are task similarity, task difficulty, and practice. Two tasks are performed
well together when they are dissimilar, when they are relatively easy, and
when they are well practised. In contrast, the worst levels of performance occur
when two tasks are highly similar, rather difficult, and have been practised
very little.
Several theorists have argued that practice leads to automatic processing. It
is generally assumed that automatic processes are fast, that they do not reduce
the capacity available for other tasks, and that there is no conscious awareness
of them. Logan (1988) proposed that increased knowledge about what to do
with different stimuli is stored away with practice, and that automaticity occurs
when this information can be retrieved very rapidly.
Absent mindedness or action slips occur as a result of attentional failure.
What often happens is that an individual runs off a sequence of highly prac-
tised and over-learned motor programmes. Attentional control is not required
during the time each programme is running, but is needed when there is a
switch from one programme to another. Failure to attend at these choice points
can lead to the wrong motor programme being activated, especially if it is
stronger than the appropriate programme. As optimal performance requires
very frequent shifts between the presence and absence of attentional control, it
is perhaps surprising that action slips are not more prevalent.
Most theory and research on attention are limited in various ways. Many of
the major issues studied in attention research become relatively meaningless
when it is accepted that attention is not unitary but rather involves multiple
systems. Attention is closely bound up with motivation in the real world, but
this interdepence of attention and motivation is not reflected in most theories
of attention.
References
Allport, D. A. (1989). Attention and performance. In G. Claxton (Ed.),Cognitive psychology: New
directions.London:Routledge&KeganPaul.
Allport, D. A. (1993). Attention and control: have we been asking the wrong questions? A critical
review of twenty-five years. In D. E. Meyer & S. M. Kornblum (Eds.),Attention and Perfor-
mance(Vol. XIV). London: MIT Press.
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