PDF (PhD Thesis Susan Chipchase) - Nottingham eTheses ...

emembered than neutral objects. The weapon focus effect (Loftus et al., 1987)
is the phenomenon that criminal incidents involving the presence of a weapon
will have a negative impact on eyewitness memory of details such as the
perpetrator’s facial characteristics and clothes. Hope & Wright (2007)
suggested that in order to clarify the components of the weapon focus effect the
roles of emotion and novelty must be disentangled. The weapon focus effect is
similar to the emotional effects being investigated here with the enhancement
of memory for central object details and impairment in memory for peripheral
details. These findings described above support the legitimacy of considering
the influence of novelty or unusualness of the emotional stimuli on the memory
and attentional effects being investigated.
Unusual and novel stimuli could be described as stimuli which surprise
the participant when viewed. Neural investigations have found distinct brain
regions are activated when expecting unpleasant, compared to pleasant and
neutral stimuli and there may be a specific neural network for internal
adaptation and preparation processes to enable adequate reactions to expected
unpleasant events (Herwig, Abler, Walter, & Erk, 2007). This suggests there
may be a differing impact on cognitive processes and behaviour of unpleasant
stimuli that are encountered unexpectedly.
The level of surprise experienced can be moderated by warning
participants of the nature of the next stimulus to be presented. The presentation
of warnings to participants has been shown to affect the ability to perceive
complex stimuli. Being given a cue of a specific example of the next stimulus
to be seen has improved the perception of complex objects, in a task where
participants must discriminate between normal and distorted images of famous
190