ANALISIS DE LOS RESULTADOS TABLA Nº

Significant main effects of SAT instruction (speed, accuracy) and compatibility (compatible, incompatible) are predicted. Specifically, RTs are predicted to be faster and error rates higher under speed instructions than under accuracy instructions. RTs and error rates are also predicted to be higher for incompatible than compatible trials; the classic Stroop effect. Additionally, RTs and error rates are expected to be affected by the compatibility of the previous trial, in that the Stroop effect will be reduced following an incompatible trial than following a compatible trial (indexed through a

current compatibility x previous compatibility interaction), suggesting the presence of conflict adaptation effects.

3) Group comparisons:

It is subsequently predicted that cognitive control, as measured by the emotional AX- CPT and Stroop tasks, will be affected by between-group differences in intrusive- memory experience (both frequency and consequences of the memory measures) and depressive symptomatology. On the AX-CPT, predictions which were not previously met are expected to emerge given the changes to the SOA, and the incorporation of emotional stimuli. Specifically, participants experiencing a high number of intrusive and negative memories, and scoring more highly on the other self-report measures (intrusive-memory distress, trait rumination and depressive symptomatology) are expected to show less proactive control (cue-letter processing). As a consequence of this reduced proactive control on the task, they are therefore expected to need to rely more on reactive control (target-letter processing). This would emerge as better AY performance, but impaired BX performance. As these variables are predicted to impair the maintenance of contextual information, these findings are predicted to be more pronounced in the long SOA trials. On the Stroop task, participants experiencing more memories and scoring more highly on the questionnaires are predicted to be more impacted by the irrelevant emotional information. This may be reflected through a reduced ability to use the speed/accuracy instruction to make block-by-block

modifications to behaviour (i.e. proactive control), or showing reduced behaviour modification after the experience of conflict. Previously, predictions in the thesis were that participants scoring highly on the questionnaires would show a specific deficit in proactive control. Conversely, Saunders and Jentzsch (2014) previously demonstrated that, on the emotional Stroop, participants high in depressive symptomatology, as

measured by the BDI-II, showed a deficit in their ability to modify behaviour

following conflict, i.e. a deficit in reactive control, and no deficit in proactive control. The lack of proactive control deficit was contrary to their predictions. Therefore, it remains to be determined whether any intrusive-memory related deficits on the emotional Stroop will be in proactive or reactive control.

Method: Participants:

The study received ethical approval from the University Teaching and Research and Ethics Committee (UTREC). Participants volunteered for the study through the SONA system and through adverts on the University memo bulletins. To take part, participants had to have recently experienced an intrusive memory and speak English fluently. In total 44 participants took part in the study. One participant was excluded as they reported a number of intrusive memories more than 3 SDs above the mean (reporting 70 intrusive memories during the Intrusive Memory Interview, details below). Consequently, 43 participants remained for the analysis (31 female, 12 male, age range 17-28). No other data points were more than 3 SDs above the mean and therefore no other data were excluded. Due to a technical error, only data for 42 participants is available for the AX-CPT task. Power analysis revealed that sample size of 34 would be required to detect a medium effect size at a 95% confidence interval using an alpha of .05. Participants were reimbursed £10 for their time.

Emotional AX-CPT:

Stimuli were single letters, presented on the nose of a face (100 mm x 70 mm) taken fromtheEkman and Friesen (1976) set of happy and sad faces. For both tasks, faces were masked to remove hair, body and any background information. The faces were

letter consisted of either an A or a B letter, and target letters consisted either an X or a Y. The target-letter required a left-handed ‘target’ response (keyboard letter z) only if preceded by the letter A. Any other cue-target pair required participants to make a right-handed ‘non-target’ response (keyboard letter m). Each trial began with a fixation cross on screen (300 ms), followed by the cue-letter (300 ms), followed by a SOA (either 1000 ms or 10 000 ms), followed by the target-letter (presented until response) and finally the screen was blank (300 ms). See Figure 6.1 for an example of a single trial sequence below.

Figure 6.1. An example of single trial sequence in the Emotional AX-CPT task

The task consisted of 2 blocks, each containing 108 trials. At the end of each block participants could take a short break. 70% of the trials were AX trials, and the rest were divided equally between AY, BX and BY trials (10% each). Within those frequencies, half of the cue-target combinations were presented on a happy face, half

were presented on a sad face. The cue-target letter pairs were always presented on the same face, displaying the same valence. After being taken through the instructions, participants began with a practice block consisting of 10 cue-target letter pairs and were given feedback after each practice trial. They were subsequently given the opportunity to ask the researcher any questions before beginning the experimental trials.

Emotional Stroop task:

The stimuli were presented centrally on screen. The stimuli set consisted of 16 faces; 4 male, 4 female, each with a happy and a sad version (Ekman & Friesen, 1976). The faces measured approximately 60 mm x 35 mm. The word ‘HAPPY’ or ‘SAD’ (printed in capital letters) was presented below each face, see Figure 6.2 for an

example. Each letter measured approximately 10 mm x 7 mm. Participants completed two blocks, each made up of 200 stimuli and could take a short break between each block. Stimuli were presented until response, and between each trial, a fixation point appeared for 1500 ms. At the beginning of each block, participants were instructed to respond as quickly or as accurately as possible and these instructions were reversed for the subsequent block. Participants were instructed to make either a left-handed (keyboard letter z) or right-handed response (keyboard letter m) depending on

whether the face was happy or sad. This was balanced across participants. After being provided with the instructions participants completed 8 practice trials and continued onto the experimental trials.

Figure 6.2. An example of a compatible condition in the Emotional-Face Stroop task.

Procedure:

After providing informed consent, participants completed the two computer tasks in a randomized order. Participants were then taken through the Intrusive Memory

Interview and completed the IES, RRS and BDI-II, in a randomized order. Next participants were given the instructions for keeping the diary over the next 7 days, after which they returned to the research laboratory to hand in their diaries and to be debriefed and reimbursed for their time.

Results:

1) Overall task data: