Reduction Of Stroop Effect Research Articles

Neurocognitive mechanisms of affective conflict adaptation: An event related fMRI study.

Control of conflict can be seen in reduced effects of conflict following incompatible trials known as conflict adaptation. Such control mechanisms have been shown to depend on emotional content present in stimuli, which could be a motivational force for control adjustments. We explored the neural mechanisms of the interaction between proactive control in terms of conflict adaptation effect and emotions through an event related fMRI study involving an emotional Stroop effect (facial expression-emotional word paradigm) involving happy and angry expressions. Conflict adaptation was measured in terms of the reduction in Stroop effect as a function of previous trial congruence and previous trial emotion. Participants responded to the facial expression while ignoring the distractor word written over the face. Behavioral results showed larger Stroop effect for angry faces compared to happy faces. Conflict adaptation effect was greater for angry faces and was also influenced by previous trial emotion. Both priming and adaptation effects were observed. Stroop effect was correlated with activations in dorsal anterior cingulate. Emotion effect was correlated with activations in amygdala, fusiform face area (FFA), and insula along with the expected hemispheric asymmetry for positive and negative emotions in left vs right FFA, respectively. Conflict adaptation effect was correlated with activations in amygdala. In addition, activations in striatum supported the three-way interaction between emotion, previous and current trial congruence. Activation in dorsal anterior cingulate was correlated only with the overall Stroop effect in the current trial. Activations in amygdala and striatum were also found with facial expressions. The results indicate that emotion specific processing areas themselves such as amygdala and striatum may self-regulate and contribute toward enhanced proactive control mechanisms for task-relevant emotional stimuli. These findings further confirm the strong relationship between cognition and affect in the context of conflict monitoring and adjustments in cognitive control.

A brief review of three manipulations of the Stroop task focusing on the automaticity of semantic access

Since Stroop (1935), semantic access has been seen as automatic but today this is questioned, following minor modifications of the Stroop task. Besner, Stolz and Boutilier (1997) showed that coloring a single letter differently from the others and asking the participant to name the color of this letter, significantly reduced the Stroop effect. Huguet, Galvaing, Monteil and Dumas (1999) showed that another person’s presence during the test significantly reduced the Stroop effect. Raz, Shapiro, Fan and Posner (2002) showed a reduction in Stroop effect when hypnotized participants were told what would appear on the screen was not a word. These reductions suggest that semantic access of a word needs attentional resources, and is not automatic. This review summarizes recent results concerning reduction of the Stroop effect through the three manipulations mentioned above. The similarities and conflicts of these studies are illustrated. The conclusions suggest that these manipulations seem not to reduce or prevent automatic semantic activation, but rather reduce non-semantic task-relevant response competition. Using measures other than behavioral measures like Event-Related Potentials and a new definition of automaticity are proposed to understand better the different results cited.

Neurophysiological Correlates of Post-Hypnotic Alexia: A Controlled Study with Stroop Test

To clarify whether hypnotically-induced alexia was able to reduce the Stroop effect due to color/word interference, 12 volunteers (6 with high and 6 with low hypnotizability according to Stanford Hypnotic Susceptibility Scale Form C) underwent a Stroop test consisting of measuring, both in basal conditions and during post-hypnotic alexia, the reaction times (RT) at appearance of a colored word indicating a color. In basal conditions, RT were greater in case of incongruence. In highly hypnotizable participants, the interference was less pronounced during post-hypnotic alexia (−34%, p = 0.03). During alexia, late positive complexamplitude was also greater for congruent than incongruent conditions (p < 0.03), and cardiovascular response to stress was less pronounced as well. In participants showing low hypnotizability, no reduction of Stroop effect was detected during post-hypnotic alexia. Post-hypnotic alexia is therefore a real and measurable phenomenon, capable of reducing the color-word interference and the haemodynamic effects of the Stroop test.