Effects of Bilateral Eye Movements and Shifts of Attention on Recognition Memory in Younger and Older Adults

There is evidence that making 30 seconds of bilateral eye movements improves memory in young adults who are strongly right-handed. The proposed neural mechanism underlying this effect is an increase in interhemispheric communication. Given that attention and eye movements share many overlapping neural mechanisms, it is possible that bilateral shifts of covert visual attention may have similarly beneficial effects on memory. To test this idea, the present investigation compared performance on a verbal recognition task following either overt shifts of attention (eye movements) or covert shifts of attention in right-handed younger and older adults. Additionally, the effects of increasing the duration of the overt and covert shifts from the typical 30 seconds to 60 seconds was examined to investigate if doubling the shift time produced a greater memory benefit than that observed at 30 seconds. Finally, to provide a greater understanding of the time-course of the effects of bilateral attention shifts on recognition memory, two different delay conditions were directly compared – one with no delay between study and test, and the other with a 30 minute delay. Both overt and covert shifts of attention led to a reduction in false memories on the verbal recognition task for the younger adults in the no delay condition. There were no beneficial effects on memory for either shift type in the 30 minute delay condition. Also, unlike the beneficial effects observed in the younger adults, there were no memory benefits for either shift type in the older adult group, and instead there was evidence that overt shifts of attention were related to an increase in false memories for the latter group. These findings are consistent with theories that suggest common neural pathways for covert and overt visual attention and with those that posit an age-related breakdown in interhemispheric communicatio