Which of the following theories suggests that the Partial Reinforcement Effect may really be just an illusion?
That is, intermittent reinforcement only appears to be more resistant to extinction because we failed to account for the fact that multiple behaviors could constitute a single response.

Explanation:

Extinction of a reinforced behavior occurs at some point after reinforcement stops, and the speed at which this happens depends on the reinforcement schedule. Among the reinforcement schedules, variable-ratio is the most resistant to extinction, while fixed-interval is the easiest to extinguish.

Just like variable ratios, variable interval schedules also produce steady rates of behaviors because the individual does not know how much time will pass until reinforcement is delivered. This creates high resistance to extinction.

In behaviorism, Intermittent Reinforcement is a conditioning schedule in which a reward or punishment (reinforcement) is not administered every time the desired response is performed. Gambling is an example of intermittent reinforcement.

The partial reinforcement extinction effect (PREE) is characterized by a tendency for subjects to perseverate in behavioural responding to a greater degree when the behaviour was previously probabilistically/infrequently rewarded as compared to when it was unconditionally/frequently rewarded.

Response unit hypothesis

Explanation:

Response unit hypothesis   by Jones and Mowrer in 1945 is a theory that suggested that, various individuals response, sent out in extinction, will increase the response unit-length, such that its numbers will be independent of response unit length.They further argued that when reinforcement follows a sequence of responses, that entire sequence forms a single functional response, or response unit. Hence, the theory suggested that the Partial reinforcement effect may be an illusion.

In other words, the response unit for extinction appears more identical to the response unit for partial reinforcement than for continuous reinforcement, this implies that, partial reinforcement effect only appears to increases resistance to extinction, such that, often times, we failed to realized that multiple behaviors could constitute a single response.