Conflict Interference in an Insect

Response conflicts occur when the correct goal-congruent response is weaker than an alternative but incorrect response. To overcome response conflicts, the stronger response has to be inhibited, making the study of response conflicts an important research topic in higher order cognition. Response conflicts often result in conflict interference-an increase in error rates and response times. Here, we ask whether an invertebrate-the ant, Lasius niger-can solve such response conflicts and, if so, whether it suffers from conflict interference. We also ask whether ants show congruency sequence effects, where subjects show transiently reduced conflict inference when conflicts repeat. We developed task-mimicking aspects of the Stroop color-word test, in which ants must learn to follow a neutral cue (a scent) on a Y maze but ignore a dominant and innately meaningful signal (a pheromone trail). The pheromone can be congruent with the scent cue (lead to the same maze arm) or be incongruent. Both accuracy and task-solving latency suffered when the information sources were incongruent. There was no evidence of congruency sequence effects. Because of limitations of the experimental design, we cannot rule out that insects would also show a congruency sequence effect under a different experimental paradigm. Although the methodology is not directly comparable to human studies, the presence of clear conflict interference suggests parallels between insect and human information processing, in spite of completely different brains. This powerful and straightforward methodology opens the possibility of exploring conflict interference in the presence of prepotent response tendencies in an invertebrate model. We hope this work encourages the field of response competition to use the vast literature on response competition in animal behavior studies.