Interrogations-and-Confessions-Handbook

356 A Psychology of Interrogations and Confessions
suggestions (Loftus, 1981). For positive reinforcement to work the suggestions
have to be obvious so that people know what they are being reinforced for. This
poses problems for the principle of discrepancy detection. Schooler and Loftus
overcome this by suggesting two conditions where people may be influenced by
obvious suggestions:
1. there may be situations where people do detect discrepancies between what
they observed and what is suggested to them, but they nevertheless decide
to comply with the interrogator;
2. obvious suggestions may be accepted and incorporated into recollections
when people have little memory for the original detail. Where memory is
very poor for a particular detail the suggestion may be quite obvious without
the person detecting any kind of a discrepancy.
Here, witnesses may recall having accepted a suggestion and may, in response to
positive feedback, become increasingly suggestible in the future (p. 109).
Schooler and Loftus make no attempt to explain the expectation component of
the Gudjonsson–Clark model in terms of discrepancy detection. The reason for
this is undoubtedly that this component of the model cannot easily be explained
by the principle of discrepancy detection. Indeed, the Gudjonsson–Clark model
would predict that failure in discrepancy detection is a necessary but not a
sufficient condition for people to yield to suggestions. This limitation or weakness
of the discrepancy detection principle appears to be completely overlooked
by Loftus and her colleagues. In other words, people may fail to detect discrepancies
between what they observed and what is subsequently suggested to
them, but this does not inevitably mean that they accept misleading information
and incorporate it into their memory. After all, people can state that they
do not know a particular answer after failing to detect a discrepancy.
In my view, the main advantage of the principle of discrepancy detection is
that it highlights a central cognitive mechanism that has an important function
in mediating suggestibility. However, as this discussion demonstrates, there is
more to interrogative suggestibility than discrepancy detection. The implication
of Schooler and Loftus that Gudjonsson and Clark could have been more
economical in the description of their model is intuitively attractive, but in reality
interrogative suggestibility is a more complex phenomenon that probably
requires more than one model for complete understanding. It seems that by
attempting to explain interrogative suggestibility comprehensively in terms of
one cognitive mechanism, Schooler and Loftus are over-ambitious and overlook
the complexity of the phenomenon. The main theoretical difference between
the Gudjonsson–Clark model and the conceptual framework of Schooler and
Loftus is that Gudjonsson and Clark postulate that suggestibility is mediated
by a number of cognitive and personality variables, rather than relying on one
central mechanism.
Irving (1987) describes his own approach to police interrogation as ‘interrogation
watching’ (p. 19). This reflects his observational study of interrogation
techniques at Brighton Police Station (Irving, 1980). His comments on