Can some types of amnesia arise, ironically, from remembering too much? And can this excessive memory impair our ability to perceive things? In a paper in Neuron, a team led by Morgan Barense (formerly at CBU, now at University of Toronto), Rik Henson (CBU, seen left), Lisa Saksida and Tim Bussey (University of Cambridge) and colleagues at Addenbrooke’s Hospital showed that amnesic patients with damage to a part of their brain called the medial temporal lobe had difficulty discriminating two similar visual objects, even when the objects were presented simultaneously (i.e, with no explicit requirement to remember). The team’s explanation was that, because the features that comprised the objects had been repeated from previous trials, their persistence in memory caused interference in the perception of the current objects. In support of this account, when the visual objects shown in intervening trials did not share the same features, the patients’ performance could be recovered to normal levels. Brain scanning of healthy individuals performing the same task implicated a specific region in the medial temporal lobes called the perirhinal cortex. These data support a theoretical framework in which visual representations get progressively more refined along the visual pathway of the brain, from coding simple features at early points in this pathway, to more complex conjunctions of features in brain regions like the perirhinal cortex that sit at the apex of this pathway. Healthy individuals can use these conjunctive representations to overcome interference between objects that share the same features, but patients with damage to this brain region cannot, so suffer from greater interference. These data highlight the complex interplay between memory and perception, and may help design environments that help patients with amnesia (e.g, see commentary by Baxter in same issue of Neuron and coverage by ScienceNews).