- seCtIon tHRee: BoDY AnD WoRLD
Another study soon afterwards (Castiello, Paulignan, and
Jeannerod, 1991) found out more by timing both motor
responses and subjective awareness in the same experi-
ment. Participants sat at a table facing three translucent
dowels, any of which could light up. Their task was to watch
for a light, shout ‘Tah’ as soon as they saw it, and grab the
lit dowel as fast as they could. In the first session, a single
dowel was lit many times and motor and vocal reaction
times were measured. In a second session of 100 trials,
the central dowel was always lit first, but then 20% of the
time the light switched to a different dowel as soon as
their hand began to move, so that they had to correct their
movement.
Reaction time to the initial movement was always about
300 ms, and then in trials where the light switched, a
movement correction occurred about 100–110 ms later.
On these trials, the participants shouted twice: when the
central dowel lit up, the vocal reaction time was 375 ms
(the same as in control trials); when the light moved, it
was about 420 ms. In other words, the movement was
corrected long before the shout that meant ‘I’ve seen it!’
The authors argued that the vocal response indicated
when the participants became conscious of the light, and
concluded that ‘neural activity must be processed during
a significant and quantifiable amount of time before it
can give rise to conscious experience’ (p. 2639). As one of
them later put it, ‘our consciousness has to play catch up’
(Jeannerod, in Gallagher, 2008, p. 244).
There are problems with this conclusion. Fast reaction times
can be obtained without awareness, so the shout might
have been initiated before the participant consciously saw
the light move, in which case consciousness might have
come even later than estimated. Alternatively it might
have come earlier and the full 420 ms have been needed
to produce the response. We cannot know because this
method does not allow us to precisely time the ‘moment of
awareness’.
Perhaps, as we suggested in Chapter 5, we should be even
more critical and question the very notion of there being a
‘moment of awareness’ or a time at which the light comes
‘into consciousness’, because this implies a mental world in
which conscious events happen alongside the physical world
of brain events. We will return to the question of how to time
conscious awareness in Chapter 9. Despite these doubts
about timing, the results suggest a dissociation between fast
motor reactions and conscious perception. One explanation
is that the two are based on entirely different systems in
the brain.FIGURE 8.7 • Venus Williams serves at speeds of up to 125 miles per
hour, yet opponents manage to respond. Is there time for a
visual signal to ‘enter consciousness’, be experienced, and
then cause a conscious response? Or is this natural way of
thinking about our actions misguided?
FIGURE 8.6 • Draw just two squares to provide each pig with its
own enclosure.