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Biological Significance in Forward and Backward Blocking: Resolution of a Discrepancy between Animal Conditioning and Human Causal Judgment

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Similarities between Pavlovian conditioning in nonhumans and causal judgment by humans suggest that similar processes operate in these situations. Notably absent among the similarities is backward blocking (i.e., retrospective devaluation of a signal due to increased valuation of another signal that was present during training), which has been observed in causal judgment by humans but not in Pavlovian responding by animals. The authors used rats to determine if this difference arises from the target cue being biologically significant in the Pavlovian case but not in causal judgment. They used a sensory preconditioning procedure in Experiments 1 and 2, in which the target cue retained low biological significance during the treatment, and obtained backward blocking. The authors found in Experiment 3 that forward blocking also requires the target cue to be of low biological significance. Thus, low biological significance is a necessary condition for a stimulus to be vulnerable to blocking.
... Feldman (1975) found that increasing the intensity of the to-be-blocked stimulus makes that stimulus less susceptible to blocking. Similarly, Miller and Matute (1996) demonstrated that blocking is less likely if the to-beblocked stimulus is of greater "biological significance," as measured by the vigor of baseline responding to that stimulus (see also Oberling, Bristol, Matute, & Miller, 2000). In other research, LoLordo et al. (1982) found that a CS that is more relevant to the US is resistant to the blocking effect in appetitive and aversive conditioning with pigeons. ...
... Most previous studies of CS effects have not identified such a large constellation of phenomena related to the nature of the CS. The strongest precedent for our f indings comes from studies of nonsexual appetitive and aversive conditioning, showing that the use of a biologically significant CS can attenuate blocking and other stimulus competition effects (Feldman, 1975;LoLordo et al., 1982;Miller & Matute, 1996;Oberling et al., 2000). ...
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Laboratory investigations of Pavlovian conditioning typically involve the association of an arbitrary conditioned stimulus (CS) with an unconditioned stimulus (US) that has no inherent relation to the CS. However, arbitrary CSs are unlikely to become conditioned outside the laboratory, because they do not occur often enough with the US to result in an association. Learning under natural circumstances is likely only if the CS has a preexisting relation to the US. Recent studies of sexual conditioning have shown that in contrast to an arbitrary CS, an ecologically relevant CS is resistant to blocking, extinc- tion, and increases in the CS–US interval and results in sensitized responding and stronger second- order conditioning. Although the mechanisms of these effects are not fully understood, these findings have shown that signature learning phenomena are significantly altered when the kinds of stimuli that are likely to become conditioned under natural circumstances are used. The implications of these find- ings for an ecological approach to the study of learning are discussed.
... Testé séparément, le stimulus B ne produit qu'une très faible réponse conditionnée. Le blocage et le masquage ont été observés de manière consistante aussi bien dans des préparations de conditionnement pavlovien chez l'animal que dans des préparations d'apprentissage de jugement prédictif chez l'humain (ex., Aitken, Larkin & Dickinson, 2001 ;Pavlov, 1927 ;Kamin, 1969 ;Mackintosh, 1976 ;Melchers, Lachnit & Shanks, 2004 ;Miller & Matute, 1996 ;Shanks, 1985). ...
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... There are several simple human forward cue-competition experiments reported in the literature (e.g. Dickinson et al., 1984;Miller, 1996;Mitchell & Lovibond, 2002), but none of these datasets have been made openly accessible. In order to provide an openly accessible dataset, we ran a standard forward cue competition experiment. ...
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It is generally assumed that the Rescorla and Wagner (1972) model adequately accommodates the full results of simple cue competition experiments in humans (e.g. Dickinson et al., 1984), while the Bush and Mosteller (1951) model cannot. We present simulations that demonstrate this assumption is wrong in at least some circumstances. The Rescorla-Wagner model, as usually applied, fits the full results of a simple forward cue-competition experiment no better than the Bush-Mosteller model. Additionally, we present a novel finding, where letting the associative strength of all cues start at an intermediate value (rather than zero), allows this modified model to provide a better account of the experimental data than the (equivalently modified) Bush-Mosteller model. This modification also allows the Rescorla-Wagner model to account for a redundancy effect experiment (Uengoer et al., 2013); something that the unmodified model is not able to do. Furthermore, the modified Rescorla-Wagner model can accommodate the effect of varying the proportion of trials on which the outcome occurs (i.e. the base rate) on the redundancy effect (Jones et al., 2019). Interestingly, the initial associative strength of cues varies in line with the outcome base rate. We propose that this modification provides a simple way of mathematically representing uncertainty about the causal status of novel cues within the confines of the Rescorla-Wagner model. The theoretical implications of this modification are discussed. We also briefly introduce free and open resources to support formal modelling in associative learning. Keywords: associative learning, prediction error, uncertainty, modelling, blocking, redundancy effect, open science.
... Although we cannot completely rule out procedural differences as a source for the differences found in our experiment, it is important to note that there is additional evidence supporting our conclusions that has been collected by using a different procedure (see Hogarth et al., 2014). Nevertheless, procedural discrepancies between human and nonhuman subjects is a topic that has raised, and still raises, a great amount of interest for learning and comparative research (e.g., Alcalá, González, Aristizabal, Callejas-Aguilera, & Rosas, 2018;Miller & Matute, 1996;Mitchell, De Houwer, & Lovibond, 2009), and that remains an open debate deserving further research. ...
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... Fittingly, avoidance of novel tastes is acquired more rapidly when the flavor is paired with gastric distress instead of footshock (Garcia & Koelling, 1966) and selective associations like this have been observed in animals as young as 1day-old rat pups (Gemberling and Domjan 1982). Pavlovian conditioning creates associations between contiguously occurring events, but it has long been known that biologically relevant unconditioned stimuli (food or shock) become associated to a conditioned stimulus more readily than they do to biologically neutral unconditioned stimuli (tone or light), and these biologically significant cues are protected from cue competition effects (Miller and Matute 1996). That information processed in terms of its relevancy to one's biological child (surviving in the grasslands or putatively parenting that child) is better remembered than an adopted child thus appears functional given the importance of preserving one's genetic lineage. ...
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