News Release

Visual Working Memory:
Does It Run Better Half Full or on Empty?

If you've been working all day on an important document and hit Save, it may seem like it takes forever for your computer to store the file to its hard drive. The more "old" data clogging your computer, the longer it takes to commit a new one to memory. New research shows that, unlike computers, when it comes to short-term memory, our brain can process and store new information just as quickly and efficiently when storing old data as when starting with a clean slate.

Decades ago, classic research showed that the process of committing a picture to working memory (which is where short-term information is stored and where long-term memories are recalled) took more time, the more complicated the picture. Nevertheless, very little has been known until know about how long it takes to process visual information when the visual storage room of the brain is partially taken up by other images. If indeed the different processes involved in visual memory—consolidation (encoding information) and maintenance (storing the information)—draw upon common resources in the brain, as traditionally believed, then the brain ought to be less efficient in processing new information when part of the memory is already being used.

But a new study by Geoffrey F. Woodman, of Vanderbilt University, and Edward K. Vogel, of the University of Oregon, shows that even if your short-term visual memory is holding a record of one image, it can store and maintain a second image just as quickly.

The research findings are reported in "Fractionating Working Memory: Consolidation and Maintenance are Independent Processes," an article in the February 2005 issue of Psychological Science, a journal of the American Psychological Society.

In one experiment, the authors required subjects to remember simple objects (black shapes) that were flashed for a fraction of a second on a computer screen and then masked by other, more complex objects (black-and white-checked shapes). The masks allowed the researchers to interrupt the storage of information into the visual working memory so they could estimate the rate of information buildup in the system. After a short interval in which participants had to retain the information, they were given a memory test. In a second experiment, Woodman and Vogel estimated the speed with which information could be stored in short-term memory when subjects were asked to remember a set of masked items (the black-and white-checked shapes) in addition to the first simple set of objects (the black shapes). This allowed the authors to determine whether the rate of short-term memory encoding was slower when information was already being maintained in short-term memory.

If visual working memory processing were slowed down by the simultaneous maintenance of earlier information, there would be an increased likelihood that we would fail to become aware of important events fast enough to use the information. For example, if your working memory were bogged down by images of cars surrounding you in rush hour, you might fail to see a potentially dangerous truck racing toward you in time to act. As the authors state, "these results demonstrate that when a looming truck appears in your rearview mirror when you are surrounded by several other vehicles in traffic, you can just as quickly become aware of this danger as when your short-term memory is unoccupied".

Download Report. For more information, contact Woodman at geoffrey.f.woodman@vanderbilt.edu.

Psychological Science is ranked among the top 10 general psychology journals for impact by the Institute for Scientific Information. The American Psychological Society represents psychologists advocating science-based research in the public's interest.

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