On the differences in degree of renewal produced by the different renewal designs

Abstract

This paper addresses sources contributing to the differences in the degree of recovery from extinction observed with different renewal paradigms. In two lick suppression experiments with rats, we assessed the role of the associative status of the acquisition context in both the weakness of AAC renewal and the sometimes observed weaker renewal resulting from an ABC design relative to an ABA design. In Experiment 1, we observed that AAC renewal relative to an AAA control group was small unless Context A had undergone associative deflation (i.e., extinction of Context A). Deflation of Context A not only decreased behavioral control by the CS in the AAA condition, but increased it in the AAC condition, thereby implicating a comparator process in addition to associative summation between the CS and test context. In Experiment 2, an excitatory acquisition context was found to enhance the difference between ABC and ABA renewal. Associative deflation of the acquisition context decreased ABA renewal more than ABC renewal. Thus, the associative value of the acquisition context (A) was more positively related to the level of renewal when the target CS (X) was tested in this context than when it was tested in a neutral but equally familiar context (C), consistent with the frequently observed greater renewal in an ABA condition than an ABC condition arising from associative summation of the CS and test context. These findings demonstrate that the excitatory status of the acquisition context influences the observed degree of renewal.

The functions of contexts in associative learning

“…As predicted by the extended comparator hypothesis, the increase was larger after 50 training trials than after 5 training trials, resulting in an interaction between amount of training and context extinction. This experiment suggests that, at least with the parameters employed, the context had a function akin to that of a discrete cue in forming a direct association with the outcome (although that was not directly measured in these experiments because testing was conducted outside of the training context), and importantly that it competed for control with the target CS such that context extinction resulted in changes (an increase) in behavioral control by the discrete CS (see Polack, Laborda, & Miller, 2013, for corroborating data).…”

“…In the condition in which trials were relatively massed during training, stimulus control by the CS was stronger in the training context than in the alternative context. This could be attributed to massed training establishing the context as a competing stimulus for the discrete cue, and summating at the time of test (see Polack et al, 2013), but this is not likely as both contexts (same or different) received similar amounts of training, and with similar ITIs in each subject. Thus, the massed condition, despite using parameters that resulted in context competition (as suggested by the context extinction data, see above), also revealed positive modulation by the context that cannot be attributed to differences between the contexts in associative strength to the US (also see Rescorla, 2008).…”

“…For example, test contexts as cues can either add or subtract from responding to the target CS. Associative summation of contexts and CSs has been demonstrated extensively in the excitatory domain (e.g., Balaz et al, 1981, 1982; Polack, Laborda, & Miller, 2013), and recently it has been shown that under certain conditions a context in which extinction occurs can acquire inhibitory properties, ultimately passing summation and retardation tests for inhibition (Polack, Laborda, & Miller, 2012). Thus, the presence of an excitatory or inhibitory context can add or subtract to responding to a discrete CS, following relatively well established principles of associative summation.…”

“…For example, in fear conditioning, contexts in which animals have received a mild footshock will elicit a freezing response, which is understood as reflecting fear to the context (e.g., Fanselow, 1980). When discrete CSs are tested in such contexts, fear to the context summates with fear to a discrete CS (e.g., Balaz et al, 1981, 1982; Polack, Laborda, & Miller, 2013). Contexts acting as cues may also interact with discrete stimuli by entering into competition with these cues, as is most evident when training trials are massed (e.g., Barela, 1999; Miguez, Witnauer, Laborda, & Miller, 2014), or when USs alone are administered before (e.g., Randich & Ross, 1984) or during conditioning (e.g., Rescorla, 1968; Miguez, Witnauer, & Miller, 2012; Urcelay & Miller, 2006).…”

“…Contexts acting as cues may also interact with discrete stimuli by entering into competition with these cues, as is most evident when training trials are massed (e.g., Barela, 1999; Miguez, Witnauer, Laborda, & Miller, 2014), or when USs alone are administered before (e.g., Randich & Ross, 1984) or during conditioning (e.g., Rescorla, 1968; Miguez, Witnauer, & Miller, 2012; Urcelay & Miller, 2006). In some circumstances, the cue-like properties of a context as a direct predictor of a US and as a cue that competes with discrete CSs may interact (Polack et al, 2013). Finally, by establishing a negative contingency between a particular context and the absence of shock, context can also acquire conditioned inhibitory properties evidenced by summation and retardation tests (a canonical pair of procedures to assess conditioned inhibition; Rescorla, 1969; Polack, Laborda, & Miller, 2012).…”