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

less than one second, whereas mood induction normally takes many seconds to
develop. They suggest that the slow effects they found may be interpreted as
negative stimuli preventing the disengagement of attention or that interference
may result from preparation to respond to a threat which may be demonstrated
through interference to a subsequent stimulus.
In the experimental design used here it will not be possible to assess the
interference from a slow effect of emotional disruption as an interstimulus
interval of no more than 32 milliseconds was found to be necessary (McKenna
& Sharma, 2004) for these effects to occur. In the paradigm used there is at
least 2 seconds between each stimulus presentation as a result of the fixation
crosses shown before and after each stimulus. Increasing the intertrial trial
interval has been shown to reduce the interference from negative stimuli and
intervals of 1 second were found to produce a disruption of only 11
milliseconds (Sharma & McKenna, 2001). This suggests that any slow effects
of interference are unlikely to have any impact on the experimental design
here.
It is possible that the fast effects of interference from emotional
disruption within a trial may be a contributory factor to the lack of memory for
peripheral details of negative emotional stimuli. It has been proposed that these
interference effects in the emotional stroop are due to the automatic attention
grabbing of emotional stimuli which leads to a reduced response time to the
task (e.g. Williams et al, 1997). It is possible that there is automatic grabbing of
attention by the negative objects in a scene which then interferes with the
processing of the backgrounds of these stimuli, leading to impaired memory for
these peripheral details.
188