Human self-control research is typically modelled by using a token economy system in which human participants choose between tokens for one choice and usually more tokens for a delayed choice. Different results were being obtained for humans and non-humans, with the latter appearing to maximize their overall reinforcement despite delays, with the former being sensitive to changes in delay. The difference in research methodologies with humans - using tokens or conditioned reinforcers - and non-humans using sub_primary reinforcers suggested procedural artifacts as a possible suspect. One aspect of these procedural differences was the delay to the exchange period (Hyten et al 1994). Non-human subjects can, and would, access their reinforcement immediately. The human subjects had to wait for an "exchange period" in which they could exchange their tokens for money, usually at the end of the experiment. When this was done with pigeons they responded much like humans (Jackson & Hackenberg 1996).

Most of the research in the field of self control assumes that self control is in general better then impulsiveness. Some developmental psychologists argue that this is normal, and people age from infants, who have no ability to think of the future, and hence no self control or delayed gratification, to adults. As a result almost all research done on this topic is from this standpoint and very rarely is impulsiveness the more adaptive response in experimental design.

More recently some in the field of developmental psychology have begun to think of self control in a more complicated way that takes into account that sometimes impulsiveness is the more adaptive response. In their view, a normal individual should have the capacity to be either impulsive or controlled depending on which is the most adaptive. However, this is a recent shift in paradigm and there is little research conducted along these lines (Logue, 1995).

References:

• Hyten, C., Madden, G. J., & Field, D. P. (1994). Exchange delays and impulsive choice in adult humans. Journal of the Experimental Analysis of Behavior, 62, 225-233.
• Jackson, K., & Hackenberg, T. D., (1996). Token reinforcement, choice, and self-control in pigeons.Journal of the Experimental Analysis of Behavior, 66, 29-49.
• Logue, A.W. (1995). Self-Control: Waiting Until Tomorrow For What You Want Today. Englewood Cliffs, NJ: Prentice Hall