Localization of position within a homogeneous behavior chain: Effects of error contingencies

Rats' localization within a homogeneous behavior chain was investigated by differentially reinforcing food-tray entries on the basis of their location within a lever-press chain. Variables of major interest were the minimum number of lever presses required for a reinforced tray entry and error contingencies. The error-contingent events manipulated were timeout and initialization of the lever-press requirement. Following reinforced tray entries, number of lever presses preceding the next tray entry was a direct function of the minimum lever-press requirement, except when errors had no programmed consequences. In the latter case, location of tray entries progressively undershot the minimum press requirement. Following nonreinforced tray entries, the number of lever presscs to the next tray entry was related to the minimum press requirement only if errors initialized the minimum requirement. These results, as well as various sequential dependencies, were considered in light of the unitary-response hypothesis and the response chaining hypothesis. Particular consideration was given to the implications of these results for a response-unit analysis of the effects of partial reinforcement on extinction and for the general issue of stimulus control across homogeneous behavior chains.