5.3. The present study

We employed a novel experimental paradigm to explore emotional effects in normal participants. A colour word, an emotional face and a colour patch were displayed successively and separately with an ISI (inter-stimulus interval) of 0 ms between colour word and emotional stimulus and 90 ms between the emotional stimulus and colour patch (target). The colour patch was presented for 30 ms. Participants were asked to name the colour of the target stimulus (colour patch) after viewing a colour word and a face.

We expected to find that normal participants could more easily ignore negative task irrelevant stimuli than positive or neutral stimuli when the ongoing of target processing can not directly neutralize the processing of emotional distractor. The attentional bias effect in normal participants is observed using the dot probe detection task but is not found in the emotional Stroop task, in which irrelevant negative information competes directly with target processing demands that are maximized by attentional control. In this study, we presented the emotional stimulus prior to the target stimulus so that the processing of the emotional stimulus did not compete directly with target processing. This method ensures that the emotional stimulus cannot be so easily overwhelmed by strong ongoing target processing and is thus comparable to the original emotional Stroop task. If normal participants inhibit more easily negative information than positive or neutral information, the reaction times in colour naming task after negative information will be faster than with positive or neutral information. This task permits us to measure the influence of emotion on subsequent attention, as does the dot probe detection task. However, while the dot probe task implicates initial attentional orienting and avoidance of locations associated with negative information, our task reveals the modification of attentional resources to targets after processing emotional content.

Priming with an emotional stimulus before presenting the simple colour patch cannot be done because there would easily be sufficient attentional resources for both the task and the irrelevant stimulus. We preserved the Stroop conflict condition as the form of colour word priming because distributed attention may be expected to result in stronger priming or distractor effects (see Musch & Klauer, in press). We also chose not to require the original Stroop task after simple priming of an emotional stimulus (e.g., presentation of “blue” printed in red ink after an angry face) because emotional stimuli can influence semantic processing of colour words and add undesirable complexity.