Reduced blocking as a result of increasing the number of blocking cues

Abstract

Weak behavioral control (blocking) occurs when a target stimulus (X) is paired with an outcome in the presence of a well-established signal for the outcome (i.e., a blocking stimulus). Conventional Pavlovian conditioning theories explain this effect by asserting that a discrepancy between expected and experienced outcomes is necessary for learning about X and that no such discrepancy exists in blocking situations. These theories anticipate that the effect of additional well-established signals for the unconditioned stimulus (US) should be additive. In two conditioned barpress suppression experiments using rats as subjects, the opposite result was observed. Experiment 1 provided evidence that blocking was reduced when two blocking stimuli were present during X-US pairings relative to when one blocking stimulus was present. Experiment 2 elaborated on the mechanisms underlying the observations in Experiment 1, while explaining the discrepancy between the results of Experiment 1 and prior reports of the additivity of blocking stimuli.

Protection from latent inhibition provided by a conditioned inhibitor.

“…Additionally, these data support the view that animals encode more than simple CS-US association in cue interaction situations. They are consistent with recent data from our laboratory that suggested an important role for higher-order associative chains in determining the response potential of a CS (e.g., Urushihara et al, 2005; Witnauer, Urcelay, & Miller, 2008). More generally, the present observations suggest that the prevailing emphasis on information processing at the time of acquisition to the exclusion of subsequent information processing, particularly at the time of testing, is misdirected.…”

Retrospective revaluation: The phenomenon and its theoretical implications

“…For example, VH&W and MSOP both predict enhanced blocking (i.e., reduced responding) to a target CS trained in the presence of two previously conditioned blocking cues relative to the presence of a single blocking cue. In contrast to this prediction, Witnauer, Urcelay, and Miller (2008) found that multiple companion cues counteract each other, such that training in compound with two companion cues actually has less impact on responding to the target than does training in compound with a single companion cue. In their critical experiment, Witnauer et al observed less blocking of X after Phase 1 training of A+ / B+ and Phase 2 training of ABX+, than after Phase 1 training of A+ / B+ and Phase 2 training of AX+ training.…”

“…Notably, the RR experiment was embedded in a sensory preconditioning procedure because, like backward blocking, the RR treatment was expected to reduce responding to a target cue that had previously been established as a strong excitor. For more detailed discussion of counteraction and release from it including numerous additional examples of both phenomena, see Urcelay and Miller (2006), Urushihara and Miller (2006), and Witnauer, Urcelay, and Miller (2008); however, it should be noted that some failures to observe counteraction have been reported (Nagaishi and Nakajima, 2008; Nakajima and Imada, 1999). …”

“…This has occurred despite considerable data inconsistent with it (see Witnauer, Urcelay, and Miller, 2014, for a review). Perhaps most notable among the behavioral observations challenging the total error reduction principle is Rescorla’s (2000, 2001, 2008) finding that two cues matched in associability (through counterbalancing) that are reinforced together in compound (i.e., same total error) change differentially as a function of their different associative strengths going into that trial. This observation strongly suggests that learning is driven by local error reduction (a.k.a.…”

Methods of comparing associative models and an application to retrospective revaluation

“…Blocking also depends on the number of compound trials; the effect is reduced with large numbers of compound training trials (Azorlosa & Cicala, 1986). Moreover, blocking fails to occur when the target stimulus is trained in compound with two previously independent excitors (Witnauer, Urcelay, & Miller, 2008). Thus, contemporary models of associative learning have been revised.…”