The Frontal Cortex

Over at the always wonderful blog Neurophilosophy, Mo has an excellent summary of a recent experiment that investigated the impressive prescience of our unconscious recognition memory:

12 healthy participants were presented with kaleidoscopic images under two different conditions. In one set of trials, they paid full attention to the images, and were then asked to decide whether or not they had seen each of them before. In the other condition, they were made to perform a working memory task whilst the initial first set of images were presented to them - they heard a spoken number and were asked to keep it in mind, so that during the next trial they could indicate whether it was even or odd. Thus, in these trials, their attention was diverted away from the stimuli.

Thus, under the first condition, the participants are consciously aware of having seen some of the images before, and had formed explicit memories of the presented images. By contrast, during the diverted memory trials, they did not form explicit memories of the stimuli, and under these conditions reported either that they had guessed at the answer. This therefore signifies that the participants were unaware of any memories of the images presented to them.

Nevertheless, the decisions which were reportedly made by guessing were found to be significantly more accurate than those based on explicit memories of the visual stimuli,. This suggests that visual information can be encoded accurately even when one is not paying attention to it -something which has been demonstrated before - and also leads to the counterintuitive conclusion that retrieval of a memory is actually enhanced one's attention is diverted during encoding of that memory.

Got that kids? So the next time you're trying to remember something - like chemistry equations or state capitals - do your brain a favor and distract it. (I always told my mom that it was okay to do homework in front of the television - now I have empirical proof, just 15 years too late.) In the book, I give a related example that also demonstrates the power of implicit memory:

Let's say, for example, that you're given lots of information about how twenty different stocks have performed over a period of time. (The various share prices are displayed on a ticker tape at the bottom of a television screen, just as they appear on CNBC.) You'll soon discover that you have difficulty remembering all the financial data. If somebody asks you which stocks performed the best, you'll probably be unable to give a good answer. You can't process all the information. However, if you're asked which stocks trigger the best feelings⎯your emotional brain is now being quizzed⎯you'll suddenly be able to identify the best stocks. According to Tilmann Betsch, the psychologist who performed this clever little experiment, your emotions will "reveal a remarkable degree of sensitivity" to the actual performance of all of the different securities. The investments that rose in value will be associated with the most positive emotions, while the shares that went down in value will trigger a vague sense of unease