Abstract
Prior studies demonstrated that compatibility effects observed in the flanker task are modulated by conflict frequency in a trial-block: compatibility effect becomes greater when the conflict frequency in a trial-block decreases. We investigated whether the modulation of compatibility effects arises from the explicit instruction as to the appearance-ratio of compatible trials in a trial-block when the appearance-ratio of compatible trials is 50%. Sixteen students conducted the flanker task in which a letter-array was presented at a left or right visual field. Although the compatibility ratio in a trial-block was actually 50% in each visual field, the participants were told that the compatibility ratio is 75% (low conflict instruction) or 25% (high conflict instruction). The results showed that the compatibility effect was larger in the low conflict instruction than in the high conflict instruction. These findings suggests that the explicit instruction of conflict frequency modulates compatibility effect in a trial-block.
