- seCtIon tHRee: BoDY AnD WoRLD
was going blue and needed more oxygen. A month later the ten patients were
hypnotised and asked whether they remembered anything that had occurred
during their operation. Four of the ten remembered the statement almost ver-
batim, and a further four remembered something of what was said. This conjures
up visions of people being unconsciously affected by horrific scenes from oper-
ating theatres.
Generally, however, unconscious processing during full anaesthesia can be
detected, but the effects are small. For example, explicit memories for informa-
tion presented under anaesthetic may be retrieved only if testing occurs within
thirty-six hours, and have little or no effect on postoperative recovery, while prim-
ing effects may depend on the specific anaesthetic used (Merikle and Daneman,
1996; Kihlstrom and Cork, 2007).
In one fascinating technique, a tourniquet is applied to a patient’s forearm before
the anaesthetic. This means that the hand is not paralysed and patients can
sometimes have a conversation using hand signals, although afterwards they
deny ever having been awake: ‘Thus, retrospective oblivion is no proof of uncon-
sciousness’ (Alkire, Hudetz, and Tononi, 2008, p. 877). It is tempting to believe in a
pivotal point somewhere between behavioural unresponsiveness and a flat EEG
(one of the criteria for brain death) where ‘consciousness must vanish’. But EEG
indexing sometimes still yields the wrong result, for example in cases using the
isolated forearm technique. ‘Either the EEG is not sensitive enough to the neural
processes underlying consciousness, or we still do not yet fully understand what
to look for’ (p. 877).
EMOTIONAL AND SOCIAL EFFECTS
Some of the most striking experiments on unconscious perception concern the
emotional effects. It is well known that people prefer familiar things – includ-
ing simple images they have seen before. This is the ‘mere-exposure effect’
and, perhaps surprisingly, it works for subliminal stimuli, too. In a famous study
(Kunst-Wilson and Zajonc, 1980), participants were shown meaningless shapes so
briefly that none reported seeing them. Responses were measured in two ways.
In a recognition task, participants had to choose which of two shapes had been
presented before. They could not do this and scored at chance (50%). Next they
were asked which of the two they preferred, and this time chose the one they
had seen before 60% of the time. This is a good example of how two different
objective measures of awareness, neither of them a direct verbal report about the
‘contents of consciousness’, can lead to different answers.
It is tempting to ask which measure reveals what the participants were really con-
scious of. This question is a natural one for the Cartesian materialist, who believes
that there must be an answer: things must be either in or out of consciousness. An
alternative is to reject this distinction and say that there is no ultimately ‘correct’
measure of whether someone is conscious of something or not; there are just
different processes, different responses resulting from or accompanying those
processes, and different ways of measuring them. In this view, there is no answer
to the question ‘what was I really conscious of?’In a later experiment, participants had to rate a series of unfamiliar Chinese ideo-
graphs according to whether they thought each represented a ‘good’ or a ‘bad’‘Either the EEG
is not sensitive
enough to the neural
processes underlying
consciousness, or we
still do not yet fully
understand what to
look for’
(Alkire, Hudetz, and Tononi,
2008, p. 877)