Sign-Tracking Procedures and Responses

Sign-Tracking Procedures:

Sign-tracking procedures are quite simple.  A small object is a cue or signal that the food reward is about to appear.   The food reward is presented to the subject regardless of what the subject does.  Sign-tracking procedures consist of repeated pairings of the small object with the food reward, over and over again.

Sign-Tracking Procedures Resemble Drug-Taking Procedures:

Sign-tracking procedures resemble the ritual of drug-taking, in that the drug user typically will see a small object just before experiencing the rewarding effects of the drug.  For example, when having an alcoholic beverage, the user sees the cocktail glass, then, shortly thereafter, feels the rewarding effects of alcohol.

Sign-Tracking Responses:

Sign-tracking procedures produce sign-tracking responses.  The subject reacts to the small object by approaching it, then contacting it, then sniffing and gnawing and chewing it.  In other words, the subject now responds to the small object as though it were the food reward.  Note that the subject’s sign-tracking actions directed at the small object are unnecessary.  They are a waste of time and energy because they serve no purpose.  The food reward is delivered regardless of what the subject does.

Even more perplexing are numerous scientific reports that sign-tracking responses are performed, and persistently, even when the performance of the sign-tracking response results in the loss of the delivery of the reward. This is quite fascinating because it indicates that the performance of the sign-tracking response is not under the strict voluntary control of the subject.  It also indicates that the sign-tracking response can be strong enough to prevail over the intention of the subject, which presumably is to eat the real food reward.  Yet, subject after subject, in experiment after experiment, continue to lose many of their food rewards because they fail to restrain their sign-tracking responses.