| Summary: | 碩士 === 國立中正大學 === 心理學所 === 94 === Vogel, Woodman & Luck (2001) have recently reported a series of 16 experiments to examine the storage capacity of visual working memory. Their findings suggest that the capacity of visual working memory is estimated to be approximately three to four items, regardless whether or not the items comprise simple features such as colored squares, or conjunction of features such as oriented color bars. Vogel et al’s conclusions also gain support from other studies that have found evidence for the view that the units of visual working memory are object-based. However, it should be noted there were also researchers who were unable to replicate Vogel et al.’s findings. As a consequence, some researchers have proposed the ideas of "weak-object" and suggested that not only the quantity of object but also the arrangements of features can influence the estimate of capacity of visual working memory. The foregoing fixed-slot view of capacity also has been challenged by Alvarez and Cavanagh (2004), who argued for the view of flexible resources rather than fixed numbers of slots for storing information in visual working memory. The present study consists of two series of experiments that were designed to examine the capacity of visual working memory and related questions. In the first series of experiments (Experiments 1 to 6), we followed the change-detection paradigm used by Vogel et al. (2001) to estimate the capacity of visual working memory for 3-D-rendered volumetric shapes, and in doing so, attempted to offer a more definitive answer to the theoretical question of how best to characterize the units of information stored in the visual working memory. In the second series of experiments (Experiments 7 and 8), we manipulated the time available for encoding 3-D objects into the visual working memory, and examined the extent to which eye fixations can be used as reliable index for such encoding operations. The results of the first series of experiments suggest that, when the exposure duration was limited to 100 ms, the working memory capacity for 3-D volumetric shapes was about two to three items, slightly lower than that claimed by Vogel et al. for relatively simplistic stimuli they used. The storage capacity for 3-D shapes increases to the level of three to four items when the exposure duration was increased to 1000 ms. The results of the second series of experiments indicated that participants were much better at detecting changes made on previously fixated items than on those that were never fixated. Taken together, these findings lend support to a more elastic view of the visual working memory capacity that fits better with the flexible resource view, rather than the fixed-slot view.
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