Chapter
Seven
Attention
experiments in 1960. He showed participants arrays of letters briefly and then
cued them to report just one line or column from the array. They could do this
accurately, even though they did not know in advance which line or column
would be tested, and they could not report all of it. He argued that memory limits
the amount that can be reported, and that ‘observers commonly assert that they
can see more than they can report’ (Sperling, 1960, p. 26). We might alternatively
say that they are conscious of more than they can access, but is this just confusing
what should be a simple issue?
Half a century later, Ilja Sligte and colleagues showed that as soon as a stimulus
has disappeared, participants can access information from an after-image, and
after that can access a limited amount of information from a high-capacity but
fragile Very Short Term Memory (VSTM). The concept of VSTM goes back to at least
the late 1970s, but Sligte and colleagues locate it to cortical area V4, and conclude
that ‘The additional weak VSTM representations remain available for conscious
access and report when attention is redirected to them yet are overwritten as
soon as new visual stimuli hit the eyes’ (Sligte, Scholte, and Lamme, 2009). Does
this mean that the information in V4 is briefly P-conscious and then disappears
before it can become A-conscious? Does this confirm a meaningful distinction
between the two? And how do we find out? Is a more systematic first-person
practice necessary to decide whether the briefly stored information really is
phenomenally conscious, or are these third-person studies all that is required to
understand what is going on?
Experiments like these have been widely discussed ever since. Block claims that
Sperling’s participants had P-consciousness of the specific shapes of all or almost
all the letters, but without A-consciousness, that their ‘perceptual consciousness
overflows cognitive access’ (Block, 2011).
In any case, we must remember that the relationship between successfully pro-
cessing or reporting visual information and being conscious of it is far from clear.
Here we might turn to what Sperling’s participants said about their experiences –
but sadly we have only informal records about this. Block claims that they reported
seeing all or almost all the letters. But maybe they were wrong, and thought they
saw more than they did. This is the opinion of Stanislas Dehaene and colleagues
(2006). It brings us back to the sensorimotor theory of vision we encountered in
Chapter 3, and to Dennett’s multiple drafts theory (Chapter 5). In order to answer
the question of whether you are conscious of something, you attend to it, which
makes you conscious of it, giving you the illusion that you were conscious of it all
along, like the fridge light that is always on when you look.
But maybe we are making unnecessarily complicated assumptions about people’s
illusions about their own experience. Maybe we can take people’s reports about
their consciousness at face value, Stazicker suggests. Maybe they were conscious
of all the letters, but not of the specific shapes of all the letters. Maybe, then, their
reports exactly match their experiences. On this account, what the cueing did was
not make accessible some portion of an already conscious experience; instead,
it made more determinate some information in that experience. This is not the
same as claiming that, as in multiple drafts, attention exerts retroactive effects on
our conscious experience, or what we think of as that experience. In this interme-
diate view, attention exerts effects on consciousness as it happens.
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IVF
35LX
B4W
FIGURE 7.4 • Sperling (1960) showed arrays
like this very briefly and then cued
participants to report a single line
or column.