- seCtIon tHRee: BoDY AnD WoRLD
and Somers, 2004). So again, we find that where the
eyes are looking and what the focus of attention is can
be quite separate.
‘You see, but you do not observe. The
distinction is clear. For example, you have
frequently seen the steps which lead up from
the hall to this room.’
‘Frequently.’
‘How often?’
‘Well, some hundreds of times.’
‘Then how many are there?’
‘How many? I don’t know.’
‘Quite so! You have not observed. And yet you have seen. That is
just my point. Now, I know that there are seventeen steps, because
I have both seen and observed.’(Arthur Conan Doyle, Sherlock and Watson in ‘A Scandal in Bohemia’, 1891)Generally speaking, as Helmholtz long ago demonstrated, it is perfectly possible
to look directly at one object or place, and pay attention somewhere else, a skill
now called ‘covert attention scanning’, as opposed to overt scanning, in which
you pay attention where you’re looking. You can try this now by keeping your
eyes on the page and attending to a location off to one side. Different (though
interacting) brain systems seem to be involved in overt and covert orientating
of attention: the superior colliculus and frontal eye fields seem to be associated
with switches of gaze and attention, while neurons in the posterior parietal cortex
are implicated in shifts of attention occurring independently of gaze. The level
of interaction is debated, though, with some studies (e.g. De Haan, Morgan, and
Rorden, 2008) finding that the brain areas involved in covert and overt attention
shifts were virtually identical, but with higher activation levels during overt shifts.
This supports the premotor theory of attention (discussed in the next section),
which proposes that a covert shift in attention is merely an unexecuted overt
shift, using the same neural mechanisms.
These examples show that attention can be involuntarily grabbed as well as delib-
erately directed, and that attention and gaze sometimes operate together and
sometimes not. But this does not necessarily tell us anything about conscious-
ness. We might feel we have consciously chosen where to place our attention
without consciousness actually playing a causal role – for example, the feeling of
acting consciously might be a by-product or a later effect of the brain processes
that selectively direct attention. Returning to our example of the person com-
ing into the room, we might feel as though we experience the sight or sound
of the disturbance first and then consciously decide to turn round and look. But
whether this is possible may be a matter of timing, a question we return to in
Chapter 9. For now, we will briefly survey some of the numerous theories that
try to offer a framework for understanding what attention is and how it works.
Some of them have their origins in intuitive metaphors or common aspects of
experience like turning round when someone opens the door; some focus on the1Probability of getting T2correct, given T1 correct23
Frames (100 ms each)Chance performance4 567FIGURE 7.3 • An example of a prototypical
procedure used to measure
the attentional blink (AB). (a)
Depiction of the experimental
design. The targets are numbers
and distractors are letters. The
task is to detect the appearance
of a number embedded in a
stream of letters. (b) Example of
observed data representing the
AB. The graph shows percentage
correct answers for the second
target (T2) if the first target (T1)
has been correctly reported.The
attentional blink. If a sequence of
distractors is rapidly shown there
is a brief period after each correct
identification during which the
next target is less likely to be seen
(Evans et al., 2011, p. 506).