Influence Of Concurrent Working Memory Load On The Word-face Stroop Effect

Emotional conflict, due to interference by task-irrelevant emotionally salient stimuli, is stemmed from the researches of cognitive conflict. The classic of cognitive conflict are the Stroop effect and the dilution of Stroop effect. There are two typical theories to explain these effects on cognitive conflict. One is perceptual load theory by Lavie et al in 2004. It argues that the allocation of resources in selective attention is determined by the level of perceptual load in current task:if the current perception task load is low, it costs only part of the resources, and the extra resources will automatically overflow to deal with distractors, then interference effect happens;if the current perception task load is high, limited resources have been depleted, and the unrelated distracters can't be processed, then the dilution effect happens. The other is load-specific mechanism theory by Park et al in 2007. It states that whether the working memory (WM) load promotes or impairs the process of selective attention depends on how it overlaps with target or distractor processing. In a selective attention task, when WM load shares the same limited-capacity mechanism with the target processing, it leads to the lack of cognitive control and the interference effects increase; when WM load shares the same mechanism with the distractor processing, it is beneficial to the target and the interference effects dilute. However, emotional conflict, to some degree, is different from general cognitive conflict. For emotional conflict, it is doubted that how much the previous theories can explain and what kind of role WM load plays. Unfortunately, it is not clear for its processing mechanism.The word-face Stroop paradigm was widely used in the researches on emotional conflict. Therefore, in order to explore the mechanism of emotional conflict, this study investigated the influence of concurrent working memory load on the word-face Stroop effect.68 undergraduates,33 male and 35 female, aged from 18 to 25, participated in the three experiments. The word-face Stroop paradigm was the basic task, as baseline, and concurrent WM load was subtask. The reaction time in basic task was considered to be the main dependent variable. In experiment 1,3 (baseline, verbal WM subtask, spatial WM subtask)×2(emotional congruence, emotional incongruence) factorial within-subject design was used.They are requierd to judge the emotional valence of the emotion word on the face. The result of repeated measure ANOVA showed the word-face Stroop effect in the conditions of both baseline and spatial WM subtask. The dilution of Stroop effect appeared only in the condition of verbal WM subtask which was not predicted by previous hypothesis. It implied that three possible reasons led to the result, including different WM load, phonological prime or unique conflict mechanism.In experiment 2,4 (baseline, neutral-word WM subtask, emotional-word WM subtask, priming subtask)×2 (emotional congruence, emotional incongruence) factorial within-subject design and repeated measure ANOVA were used. They are also requierd to judge the emotional valence of the emotion word on the face.The dilution of Stroop effect still appeared only in the condition of verbal WM subtask. The word-face Stroop effect was found in the condition of emotional-word WM subtask and priming subtask. It meant that unique mechanism existed in emotional conflict and phonological prime didn't work in the word-face Stroop paradigm.In experiment 3,3(baseline, neutral-word WM subtask, emotional-word WM subtask)×2(emotional congruence, emotional incongruence) factorial within-subject design and repeated measure ANOVA were used. They are requierd to judge the emotional valence of the face behind the word.the word-face Stroop effect was found in the condition of neutral-word WM subtask.To sum up, the results showed that the word-face Stroop effect was influenced by both different working memory loads and its own processing mechanisms, especially the emotional distractor. Emotional conflict was different from the general cognitive conflict and its processing mechanism was unique. Neither perceptual load theory nor specific load mechanism was suitable for emotional conflict so that they need to be integrated.