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

data. These ideas discussed above may also help in finding an explanation for
the enhancement of memory by negative and positive emotion.
Section 6.3. Emotion and experimental stimuli
In the introduction of this thesis different ways of defining emotion and
the most appropriate criteria for defining emotion for the investigation of
cognitive processes were discussed.
Emotion has been defined in this thesis according to the opposing
dimensions of negative and positive valence. This has proved a valuable
approach with different effects on memory and attention from stimuli with
different valences. Discrete emotions such as sadness, threat, anger have also
been described as important to consider (e.g. Levine & Pizarro, 2006) and it
may be that further insight into the influence of emotion on cognition could be
gained by examining these discrete emotions. The categorisation of
photographs from the International Affective Photograph System into discrete
negative emotions of fear, disgust, sadness and anger has been conducted,
although one of the difficulties can be that the majority of emotions are a blend
of more than one of these basic emotions (Mikels et al., 2005). This blending
of different emotions can cause difficulty in interpreting the findings but would
be an avenue of research worth pursuing.
In the first two chapters of this thesis I used photographs from the
International Affective Picture System (Lang et al, 2001) as experimental
stimuli. These IAPS photographs have been used extensively in emotion and
cognition research. They are a very large source of easily accessible emotional
and non-emotional photographical stimuli. However, through my experience of
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