Brain’s Memory More Powerful Than Thought

Human brain power

Almost limitless capacity for short-term memory

by David F. Coppedge

You don’t have a limited memory that can be used up. The only limits are on how much you desire to know.

A new PNAS paper by psychologists from Harvard and the University of California at San Diego has an instructive title: “Working memory is not fixed-capacity: More active storage capacity for real-world objects than for simple stimuli” by Brady, Stormer and Alvarez. Unlike computers, which have fixed registers and RAM, the human brain seems to have almost limitless capacity for short-term memory (the kind you use when actively observing and thinking, as opposed to long-term storage). Here’s the significance of their findings:

Visual working memory is the cognitive system that holds visual information in an active state, making it available for cognitive processing and protecting it against interference. Here, we demonstrate that visual working memory has a greater capacity than previously measured. In particular, we use EEG to show that, contrary to existing theories, enhanced performance with real-world objects relative to simple stimuli in short-term memory tasks is reflected in active storagein working memory and is not entirely due to the independent usage of episodic long-term memory systems. These data demonstrate that working memory and its capacity limitations are dependent upon our knowledge. Thus, working memory is not fixed-capacity; instead, its capacity is dependent on exactly what is being remembered.

Visual working memory has limits, of course; it’s often used as a measure of intelligence. Most people struggle remembering 3 or 4 unfamiliar visual objects at a time when they are undergoing changes. When remembering familiar objects, though, people generally remember more for longer times. The researchers decided to look further into the reasons for the difference.

After running experiments with participants at Harvard asked to recall unfamiliar objects or colors compared to real-world objects, they psychologists change the paradigm about memory limits. “Overall,” they conclude, “this suggests that visual working memory does not always comprise the fixed  capacity previously described based on studies using simple stimuli but is a flexible system that varies in capacity depending on stimulus type.”…

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image credit: Mohamed Hassan