to change in each visual fixation. These mechanisms are: retinal adaptation, "pop-out" systems, and motion detectors. The implication of this view is that little information is needed to be retained between each saccade. Irwin Irwin's conclusion regarding transsaccadic memory is that there are no separate mechanisms, but that rather it is the same as short-term visual memory. Irwin's experiments showed that people cannot fuse pre-saccadic and post-saccadic images in successive fixations. These results are evidence against spatiotopic fusion. According to Irwin, there is no transsaccadic buffer that holds visual information from one fixation point to the next. Also, transaccadic memory does not hold detailed spatial information, but a more abstract representation. Irwin describes transaccadic memory as an undetailed, limited capacity memory that is relatively long-lasting. Features Visual short-term memory Many statements have been made concerning the relationship between transsaccadic memory and visual short-term memory. Researchers have noted several similar characteristics between the two systems, leading several to believe that transsaccadic memory is in fact visual short-term memory or a part of visual short-term memory. Transsaccadic memory has a limited capacity of three to four items, a slow decay rate and maskable characteristics. Basically, transsaccadic memory can hold three to four items for each saccade, and the retention of items decays or disappears from consciousness slowly after the presentation of the stimulus. However, once a mask stimulus, such as a blank screen, is presented immediately after the stimulus, the items retained prior to the mask can be replaced and/or eliminated faster by the mask. All of these factors are typical characteristics of visual short-term memory. The content stored in transsaccadic memory are less-image like, more abstract and are sparse representations of the objects, which is found to be similar to the type of representations in visual short-term memory. Transsaccadic memory is different from visual short-term memory in that it takes into account the changes of the target's location due to the eye moving to new saccades. The information retained between saccades do not take into account positional information very well. Nevertheless, relational and identity information are well retained. Prime and colleagues (2006) hypothesize, transsaccadic memory utilizes egocentric mechanisms, like selective attention, to reduce the visual search of the target and allow for spatial information between saccades to be retained and updated by incorporation of information across saccades. Attention Transsaccadic memory is characterized by the integration of information gathered prior to the