Interrogations-and-Confessions-Handbook

426 A Psychology of Interrogations and Confessions
amphetamine and MDMA (ecstasy) on mood, memory and interrogative suggestibility
using the GSS (only Yield 1 was measured). The participants were
recruited in a nightclub setting and tested in a small quiet room away from the
dance floor. Four days later the participants were re-tested at their home.
The data was analysed by the use of repeated analysis measures of variance
(ANOVA) on all the psychological variables, with day (1 or 5) as the within subjects
factor, and group (ecstasy, amphetamine or control) as a between subjects
factor. As far as the GSS scores are concerned there were two significant findings.
First, the memory scores differed significantly between the three groups,
with the amphetamine group having by far the lowest memory scores on both
occasions they were tested. The author explains this finding by the fact that
the three groups differed markedly in their level of education, with only about
one-quarter of the amphetamine group having attended university, in contrast
to 86% of ecstasy users. This is an interesting finding in itself, because it suggests
that different educational backgrounds are associated with the types of
illicit drug taken as well as the abstinence from taking illicit drugs.
The second significant finding with regard to the GSS was that, whereas
the mean Yield 1 suggestibility score was decreased on repeated testing for the
ecstasy group, the reverse pattern was found for the amphetamine group. In
other words, the participants who were under the influence of amphetamine on
day one were less suggestible on that day than they were on day five, whereas
participants who had consumed ecstasy were more suggestible on day one than
on day five. This is an interesting finding and suggests possible differential
effects of individual drugs on suggestibility.
When interpreting the findings it is important to consider the conditions
under which the participants were tested. All participants were tested in one of
two nightclubs. This has the advantage of being an environment in which both
ecstasy and amphetamine are commonly taken, but there were two potential
problems identified by the author about this setting. These relate to the fact
the participants may have been tired when tested, and the participants, apart
from one in the control group, had also taken cannabis that night. As far as
alcohol was concerned over 60% of the participants in each group admitted to
having consumed up to six units of alcohol more than four hours prior to the
testing. According to the author, none of the participants were considered to be
intoxicated at the time of testing. All participants reported similar and regular
(most weekends or more often) use of cannabis and alcohol. Nevertheless, the
potentially contaminating effects of cannabis and alcohol on the findings cannot
be ruled out. The effects of cannabis on suggestibility are not known and await
further research. Alcohol, as we shall see, has been found to reduce people’s
susceptibility to Yield 1 on the GSS (Santtila, Ekholm & Niemi, 1999).
The Effects of Alcohol Intoxication on Interrogative Suggestibility
The effects of alcohol on interrogative suggestibility have been investigated by
Santtila and his colleagues in Finland (Santtila, Ekholm & Niemi, 1998, 1999;
Santtila Alkiora, Ekholm & Neimi, 1999). They set out to investigate the effects
of alcohol on interrogative suggestibility and to identify the mediating processes