AIMS AND OBJECTIVES

The primary aim of the present study was to investigate the presence of a negative bias across two factors: Mood (dysphoric and non-dysphoric) and Age (younger adults aged between 20 and 40 years and older adults aged between 70 and 80 years). A further aim of the study was to compare the way participants rated emotionally salient images for their interpretation of ‘mood’ (sad and happy).

Eye tracking stage

Using a quasi-experimental approach, the present study partially replicated the Eizenman and colleagues (2003) study presented in Chapter 3, using a similar eye tracking method. A range of methods have been previously employed to investigate cognitive biases. Hermans et al. (1999) propose that tracking eye gaze is an effective means of assessing attentional processing, suggesting that the time spent viewing emotionally themed images relative to the mood of the individual is a valid measure of negative bias. Tracking eye movements provides a continual trace of attention allocation, which is especially worthwhile when competing stimuli are presented (Sears et al., 2011).

While tracking eye movements is a valid measure of attention allocation, there are many ways ‘time’ can be measured. In keeping with the Eizenman et al. (2003) study, the measurement of attention allocation in the eye tracking stage included three dependent variables. Firstly, the total time spent looking at each image type (quadrant) was the first measure of attention allocation. This was averaged out over the 20 experimental slides such that for each participant, the total number of raw gaze points for each of the four image types was converted to a percentage of time, summed, and then averaged. While Eizenman et al. did not convert total time to a percentage, other researchers have (e.g., Ellis et al., 2011;

Kellough et al., 2008). This dependent variable is referred to as the ‘percentage of total time’.

Secondly, the mean number of times a participant’s gaze shifted to a particular image type was calculated. This involved the number of times gaze entered, and re-entered, the

quadrant boundaries of each of the four image types. This dependent variable is referred to as ‘fixation frequency’; it provides a clearer understanding of attentional and negative biases providing information about how often attention is drawn to particular image types.

Noteworthy, a ‘fixation’ is determined by the number of times an individual looks at an area for a specified time, determined as 100 milliseconds (or more).

The final dependent variable is referred to as ‘average glance duration’. This is defined as the average amount of time each participant’s gaze stayed within the boundaries of a particular image type for each fixation, and is reported as a percentage of time. A computer programme was written that recorded the order the images were viewed, as well as the amount of time (in milliseconds) each image was viewed for that particular entry into each quadrant. The amount of time for each quadrant was summed and then divided by the number of visual entrances into that quadrant to provide an average amount of time per

entry. This was then converted to a percentage of time to provide the average glance duration. This dependent measure provides information on how long attention was allocated on average on each separate viewing occasion for a particular image type.

While each of the aforementioned dependent variables3 _{are provided as a measure of} attention allocation, it is clear that each provides a different yet complementary way of assessing negative biases. Not only was information provided on how much time was spent viewing particular image types, but information on selective attention and disengagement of attention was established also.

On the basis of previous research that has found depressed/dysphoric individuals

demonstrate a negative bias, it was hypothesised that dysphoric participants in the present study would attend to sad images for longer, fixate more frequently on sad images, and have greater average glance durations when viewing sad images than non-dysphoric participants. Conversely, non-dysphoric participants were hypothesised to attend to happy images for longer, fixate more frequently on happy images, and have greater average glance durations when viewing happy images compared to dysphoric participants.

There has been limited research investigating age-related differences in cognitive biases in those experiencing mood conditions. However, it seems that older dysphoric individuals have a tendency to attend more to negative stimuli than their non-dysphoric counterparts. It was therefore expected that older and younger dysphoric participants would exhibit similar patterns of attending to sad images. Therefore, no age-related differences were expected in the dysphoric group when sad images were viewed. However, in non-clinical samples, older adults were expected to exhibit a positivity effect, for which it was hypothesised that older non-dysphoric participants would attend to happy images for longer than younger non-dysphoric participants.

Rating stage

A novel addition to the present study was a rating component, whereby emotionally salient images from the eye tracking stage were rated for ‘mood’ (happy to sad). This task was included to provide an indication of the possible differences in interpretative biases between mood and age groups. This was important because while the negative bias findings would

3 _{Importantly, the dependent variables are not independent as average glance duration is a ‘composite’ of the}

explain what differences occur in attention, it would not necessarily explain why. For

instance, when dysphoric individuals attend to negative stimuli for longer periods of time, is it because they are hyperattentive to negative material and, as demonstrated in cognitive theory, see things through a negative framework, resulting in the selective attention towards such negative material? Or is it possible that those with depression do not interpret a

negative stimulus as negatively when compared with non-dysphoric individuals? If the latter is likely, dysphoric individuals could potentially not feel the same aversion to negative material, and therefore, the need to disengage from it would not be as great.

In drawing on the research literature surrounding interpretation biases, it is hypothesised that dysphoric participants would exhibit a negative interpretation bias, rating sad images less positively when compared to non-dysphoric participants. No age-related differences were expected. When rating happy images for mood, it was hypothesised that non- dysphoric participants would provide more positive ratings than dysphoric participants. However, the positivity effect was expected to be present within the non-dysphoric group, with older non-dysphoric participants hypothesised to provide more positive mood ratings for happy images than younger non-dysphoric participants.