Abstract

_Neural representations underlying perception and memory of low-level visual features, such as color and orientation, are quite well understood. Much less is known about how the primary visual features are integrated into objects and whether similar principles hold for object memory than for memory of primary features. In the first part of the talk, I present studies of shape perception and memory. One suggestion in the literature is that shapes are represented by the means of their radial frequency (RF) components. Using fMRI and representational similarity analysis (RSA) we showed RF specific responses patterns in the intermediate visual areas, supporting the role RF analysis in shape perception. In another set of studies, we measured the effect of RF shape amplitude and component phase difference on memory performance. For amplitude modulated shapes, memory precision gradually declined as the number of shapes to-be-remembered was increased. For two-component and phase modulated shapes, the memory performance dropped already for two items. These results suggest similar properties for memory of shapes and primary features, but highlight the role of the behavioral task on memory performance. In the second part of the talk, I present our recent study on face memory. We continuously varied facial expressions of five basic emotions and measured memory precision as a function of memory load. Happy expressions were remembered most precisely, then disgusted, fearful, angry and sad expressions. However, for each emotional expression, memory performance declined similarly as a function of memory load. Memory performance correlated more with emotion discrimination than identification. Furthermore, precision for faces did not decline when memory was loaded with gratings, suggesting separate memory systems for faces and features. In the third part of the talk, I present some ongoing work and future plans. We recently applied RSA to combine EEG and fMRI data in order to simultaneously have both high spatial and temporal resolution. I briefly describe the method and how we are going to apply it to face perception and memory._