Requirement for high-level mental processing in subliminal learning

We are constantly learning new things as we go about our lives. In addition to learning new facts, procedures, and concepts, we are also refining our sensory abilities. How and when these sensory modifications take place is the focus of intense study and debate. In new work, researchers at Boston University and the University of Montreal unify two lines of research--our understanding of classical learning and a phenomenon known as the attentional blink--to achieve an important demonstration that high-level mental processing is required even for subliminal learning.

Subliminal learning is a low-level perceptual learning process that can occur without awareness of what is learned, and it is thought to occur in manner similar to that of learning based on stimuli of which we are aware. Previous work has shown that subliminal learning can occur for motion stimuli that are paired with the targets of a letter-identification task. To investigate whether high-level processing is necessary for unconscious, automatic learning, the authors build on previous work that had identified what is known as an "attentional blink." This "blink," which is revealed when subjects attempt to identify certain images shown in rapid succession, has been shown to result from a bottleneck in high-level processing (such as decision making and memory encoding) but does not affect perceptual and semantical processing.

In the new work, published in Current Biology, Dr. Aaron Seitz and colleagues examined whether learning can occur for stimuli presented subliminally during the attentional blink. The authors show that whereas subjects are able to learn from subliminal stimuli presented outside of the time window of the attentional blink, no learning occurs for stimuli presented during the attentional blink. The authors go on to show that this lack of learning during the attentional blink is not due to a deficit of sensory processing during the blink, implying that the learning results from an interaction between high-level and low-level processing. The findings represent an important step toward increasing our understanding of the mechanisms that underlie our ability to direct attention to important environmental factors and to learn from them.

The researchers include Aaron Seitz and Takeo Watanabe of Boston University in Boston, MA; Christine Lefebvre and Pierre Jolicoeur of Université de Montréal in Montreal, Canada. This work was supported by the NSERC, CRCP, U de M., and NIH.

Seitz et al.: "Requirement for High Level Processing in Subliminal Learning." Publishing in Current Biology, Vol. 15, R753-R755, September 20, 2005. www.current-biology.com

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