Look to the left, look to the right, to the left, to the right… A review on the effect of horizontal saccades on cognitive performance

Look to the left, now look to the right, then to the left, to the right… This is essentially what is asked to the participants in the studies examining the effects of horizontal saccadic eye movements on cognitive performance, mainly on memory. It has been suggested that short (about 30 seconds) series of horizontal saccades preceding an episodic memory task appear to improve memory performance, especially in highly right-handed individuals. However, studies have not yielded conclusive evidence, sometimes showing a positive effect on episodic retrieval, sometimes failing to report this effect. As the question of whether and how bilateral saccades may modulate cognitive efficiency seems to be of undeniable interest, both on a theoretical and a clinical perspective, we aim at reviewing the existing work. The paper presents basic information about the cerebral substrates of saccade generation, a classical experimental paradigm used in the field, the main results and the different hypotheses about the cerebral and cognitive mechanisms underlying the effects. We emphasise that studies are still scarce and carried out by a limited number of teams, and attempts of explanations are still very preliminary. We also describe a research approach of “adversarial collaboration”, which we consider particularly appropriate in this context. Finally, as it seems necessary to take into account the links between this scientific study of the effects of eye movements on cognitive and cerebral functioning and the numerous publications on the effectiveness of the psychotherapies using eye movements, we propose some considerations on the treatments based on the Eye movement desensitisation and reprocessing (EMDR) approach