**Subjects** 24 for main experiment <br> Subjects will be drawn from the undergraduate course credit pool. They will participate in groups of no larger than five at testing computers separated by dividers on either side. View distance is fixed with an adjustable, custom chin rest constructed from PVC pipe and foam padding. **Stimuli** Massive Memory Database [1][2], augmented with images from Google images. All test and bait images are members of an exemplar pair; filler images are randomly drawn without replacement from the unique object set. **Display Parameters** View distance: 55 cm <br> Image size: 256 x 256 (8.5 degrees visual angle) <br> Monitor: BenQ XL2420TX (1920 x 1080 at 99.9 Hz) <br> **Task Description** Study task: 240 images, each a member of an exemplar pair, and 6 randomly chosen objects (which will not be used in later tasks) that will repeat after 10, 30, and 60 intervening images in each half of the study task. <br> View time: 3 seconds <br> Presentation: at fixation <br> A break screen occurs halfway through the study phase, pausing until subjects initiate the next portion of the study phase. <br> Response mode: Keyboard input (space bar) <br> Instructions: Watch for any repeating objects and press the space bar if one appears. A correctly identified repeat will turn green. <br> Memory and change detection: 80 trials. First array is five random filler objects and a bait item from an unstudied exemplar pair. Bait item changes into its studied complement. <br> View time: 1.2 s (200ms per prechange item) <br> Presentation: equally spaced on an annulus at 12.6 degrees eccentricity <br> Response mode: Click familiar object <br> Additional response: After each trial, subjects provide a yes/no response using the arrow keys (right for yes, left for no) indicating whether the object they selected on the previous screen changed from the first array. <br> Instructions: Try to find the familiar item in the second array. To help you spot it, you can look for an item changing between the first array and the second array. When an object changes, it will always change into a familiar object. Change detection (unstudied): 80 trials. First array is five random filler objects. Bait object is an exemplar pair that changes into its unstudied complement in the second array. <br> View time: 1.2 s (200ms per prechange item) <br> Presentation: equally spaced on an annulus at 12.6 degrees eccentricity <br> Response mode: Click changed object <br> Instructions: Find the object in the second array that changed from the first array. Memory test (6AFC): 80 trials. Array of five random filler objects and one studied exemplar.<br> View time: unlimited <br> Presentation: equally spaced on an annulus at 12.6 degrees eccentricity <br> Response mode: Click familiar item Memory test (2AFC): 80 trials. Studied exemplar presented with its unstudied complement as a foil.<br> View time: unlimited <br> Presentation: Presented side-by-side at 15.8 degrees eccentricity <br> Response mode: Arrow keys indicate studied item **Data** During the object study phase, we will collect whether a subject failed to respond to a repeated object, incorrectly identified a unique item as a repeat, or correctly identified a repeat. We will also note where in the images the response image occurs and where the first appearance of the object occurred. For the change detection and memory trials, percent accuracy is the measure of interest. We will also examine the percentage of time subjects reported seeing their selected object change in the memory-change detection hybrid task. **References** <br> [1]: http://cvcl.mit.edu/MM/stimuli.html <br> [2]: Brady, T.F., Konkle, T., Alvarez, G.A., & Oliva, A. (2008). Visual long-term memory has a massive storage capacity for object details. *Proceedings of the National Academy of Sciences,105* (38), 14325-1432.