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The ability to form associations between different stimuli in the environment to guide adaptive behavior is a central element of learning processes, from perceptual learning in humans to Pavlovian conditioning in animals. Like so, classical conditioning paradigms that test direct associations between low salience sensory stimuli and high salience motivational reinforcers are extremely informative. However, a large part of everyday learning cannot be solely explained by direct conditioning mechanisms – this includes to a great extent associations between individual sensory stimuli, carrying low or null immediate motivational value. This type of associative learning is often described as incidental learning and can be captured in animal models through sensory preconditioning procedures. Here we summarize the evolution of research on incidental and mediated learning, overview the brain systems involved and describe evidence for the role of cannabinoid receptors in such higher-order learning tasks. This evidence favors a number of contemporary hypotheses concerning the participation of the endocannabinoid system in psychosis and psychotic experiences and provides a conceptual framework for understanding how the use of cannabinoid drugs can lead to altered perceptive states.

Sensory preconditioning means that reinforcement of stimulus A after unreinforced exposure to a compound AB also leads to responses to stimulus B. Here, we describe and analyze sensory preconditioning in an insect, the honeybee Apis mellifera. Using two-element odorant compounds in classical conditioning of the proboscis extension reflex, we found (i) that sensory preconditioning is not due to stimulus generalization, (ii) that paired, but not unpaired, presentation of elements supports sensory preconditioning, (iii) that simultaneous, but not sequential, exposure to the elements of the compound supports sensory preconditioning and (iv) that a single presentation of the compound yields maximal sensory preconditioning. The results are discussed with respect to configural and chain-like associative explanations for sensory preconditioning. We suggest an experience-dependent step of compound processing, establishing configural units, as an additional explanation for sensory preconditioning.

Two experiments on rats tested predictions of a Pavlovian conditioning model of drug tolerance which holds that tolerance is the result of compensatory conditioned responses, developed to environmental stimuli accompanying the drug administrations, which attenuate the direct effects of the drug. In Experiment I, the acquisition of tolerance-modulating properties by the tone component of a tone-light compound stimulus which accompanied morphine administrations was reduced by prior light-morphine pairings (blocking). In Experiment II, a tone stimulus acquired tolerance-modulating properties through prior pairings with a light stimulus which later accompanied morphine administrations (sensory preconditioning). These findings are uniquely predicted by the Pavlovian conditioning model of drug tolerance and are incompatible with traditional theories which assign no role to environmental stimuli present at the time of drug administration.

Value-based decisions about alternatives we have never experienced can be guided by associations between current choice options and memories of prior reward. A critical question is how similar memories need to be to the current situation to effectively guide decisions. We address this question in the context of associative learning of faces using a sensory preconditioning paradigm. We find that memories of reward spread along established associations between faces to guide decision making. While memory guidance is specific for associated facial identities, it does not only occur for the specific images that were originally encountered. Instead, memory guidance generalizes across different images of the associated identities. This suggests that memory guidance does not rely on a pictorial format of representation but on a higher, view-invariant level of abstraction. Thus, memory guidance operates on a level of representation that neither over- nor underspecifies associative relationships in the context of obtaining reward.

Recent work (Blundell et al., 2001; Balleine et al., 2003) has suggested that the basolateral region of the amygdala (BLA) is important in the representation of the sensory and incentive aspects of motivationally significant events. In common with other theories of function of the BLA, this predicts that lesions of the BLA will interfere with reinforcer devaluation after appetitive Pavlovian or instrumental conditioning. However, this hypothesis also predicts that BLA lesions will be without effect on postconditioning changes in reinforcer value if initial learning is only about the sensory aspects of otherwise neutral events. This interpretation is supported by evidence for significant detrimental effects of BLA lesions on reinforcer devaluation in a Pavlovian autoshaping procedure, but no effect of postconditioning devaluation using a sensory preconditioning procedure. These results demonstrate that animals with BLA lesions can remain sensitive to post-training changes in the motivational value of outcomes.

Successful retrieval of a memory for an entire pattern of stimulation by the presentation of a fragment of that pattern is a critical facet of memory function. We examined processes of pattern completion using novel sensory preconditioning procedures in rats that had either received sham lesions (group Sham) or lesions of the hippocampus (group HPC). After exposure to two audio-visual patterns (AX and BY) rats received fear conditioning with X (but not Y). Subsequent tests assessed fear to stimulus compounds (e.g., AX versus BX; Experiment 1) or elements (A versus B; Experiment 2). There was more fear to AX than BX in group Sham but not group HPC, while there was more fear to A than B in group HPC, but not in group Sham. This double dissociation suggests that pattern completion can be based upon separable processes that differ in their reliance on the hippocampus.

In Experiments 1 and 2, rats received initial training in which two neutral events were presented as a serial compound (A--~X). Subsequent training with A as a signal for shock was found to endow X with the ability to evoke the conditioned response of suppression. Experiment 2 also showed that responding to X was diminished if, prior to testing, Stimulus A underwent extinction. Two possible mechanisms for these findings are considered: (a) that X elicits responding through the associative chain X-A-shock, and (b) that A activates a representation of X that gains direct associative strength during conditioning with A and loses it during extinction of A. Experiment 3 demonstrated that an X-shock association established after initial A--~X training can be extinguished by nonreinforced presentations of A. These results suggest that associatively evoked representations of stimuli can enter into associations. In standard demonstrations of sensory preconditioning (e.g., Prewitt, 1967), subjects are given an initial phase of training with a serial compound event X-A, neither of the components of which has any marked motivational significance or response-eliciting power. In a second phase of training, one of the elements of the compound (A) undergoes standard Pavlovian training and, by virtue of its association with a motivationally significant unconditioned stimulus (US), comes to evoke an overt conditioned response (CR). In the final, test, phase of the procedure it is demonstrated that Stimulus X is also capable of evoking the CR. This result has been interpreted in terms of the formation of an association between X and A during the first phase of training. The second phase establishes an A-US association so that presentation of the X stimulus at test is able to contact the representation of the US (and thus evoke the CR) by way of the associative chain X-A-US. In addition, the effect can be found when A and X are presented as a simultaneous compound (e.g., Brogden, 1939; Rescorla & Freberg, 1978); in this case too, an excitatory X-A association could still be formed and might be responsible for the result observed. The remaining temporal arrangement (the backward case), in which A precedes the presentation of X, has been little studied; and to the extent that this procedure is less likely to generate the excitatory X-A association, it might be supposed that it would be unlikely to yield a sensory preconditioning effect. Indeed, with one exception, studies that have used backward pairings (i.e., A-X) in the first phase of training have failed to find any effect (Brown & King, 1969; Coppock, 1958; Tait, Marquis, Williams, Weinstein, & Suboski, 1969).

Stimulus competition (e.g., blocking) has been observed between antecedent events (i.e., conditioned stimuli or potential causes), but recent evidence within the human causal learning literature suggests that it could also be obtained between subsequent events (i.e., unconditioned stimuli or potential effects). The present research tested this hypothesis with rat subjects. To avoid confounding the antecedent versus subsequent variable with the affective value of the events involved (i.e., unconditioned stimuli are ordinarily of greater affective value than conditioned stimuli), a preparation was used in which antecedent and subsequent events all lacked affective value during the blocking phases of the study. This was achieved through the use of sensory preconditioning. Blocking of subsequent events as well as antecedent events was observed. The challenge to most associative theories that is provided by blocking of subsequent events is discussed. Copyright 1997 by the American Psychological Association, Inc.

Responding to a related pair of measurements is often expressed as a single discrimination ratio. Authors have used various discrimination ratios; yet, little information exists to guide their choice. A second use of ratios is to correct for the influence of a nuisance variable on the measurement of interest. I examine 4 discrimination ratios using simulated data sets. Three ratios, of the form a/(a + b), b/(a + b), and (a - b)/(a + b), introduced distortions to their raw data. The fourth ratio, (b - a)/b largely avoided such distortions and was the most sensitive at detecting statistical differences. Effect size statistics were also often improved with a correction ratio. Gustatory sensory preconditioning experiments involved measurement of rats' sucrose and saline consumption; these flavors served as either a target flavor or a control flavor and were counterbalanced across rats. However, sensory preconditioning was often masked by a bias for sucrose over saline. Sucrose and saline consumption scores were multiplied by the ratio of the overall consumption to the consumption of that flavor alone, which corrected the bias. The general utility of discrimination and correction ratios for data treatment is discussed. (PsycINFO Database Record

The existence of sensory preconditioning is demonstrated in cats trained to respond to a visual stimulus at the 50% level in a hurdle-box, shock avoidance situation. A comparison is made of the paradigm and apparatus used in this study with other sensory preconditioning studies.

A light and a tone were presented unpaired or paired with onset intervals of −.5, 0,.5, or 1 sec to independent groups of 18 male students. For all Ss, the second stage involved classical conditioning of GSR to tone, and the third stage tested for sensory preconditioning (SPC) in extinction trials to light. The results indicated that no SPC occurred, but on two test trials there was a significant quadratic component in the relationship of difference scores to the preconditioning interstimulus interval. It is suggested that Ss’ hypotheses about stimulus relations should be considered in SPC research with humans.

It was hypothesized that the orientation reaction mediates sensory preconditioning. The test of the hypothesis consisted of habituating the orientation reaction to the two stimuli used in sensory preconditioning in one group of rats and comparing their performance to a group whose orientation reactions were not habituated. The results clearly indicate that repeated exposure to two stimuli hinders the development of a learned association between them when they are subsequently paired and, thus, support the hypothesis.

Sensory preconditioning was first demonstrated in Pavlov's laboratory in 1931/32, rather than discovered by Brogden in 1939. Pavlov included nonassociative controls, forward pairing of the indifferent stimuli before reinforcing the second one with shock, and he avoided the development of inhibition to the compound by using a moving visual stimulus and a sound like that of scurrying mice, which both had persistent orienting reactions. Pavlov concluded that the indifferent stimuli were associated by temporal contiguity similar to human associations between successively spoken works. He did not consider the possibility of mediation via the orienting reactions.

Twenty male rats were trained to bar-press for food reinforcement. One group (N = 10) received paired presentations of white noise and light (sensory preconditioning), while the other (N = 10) received only noise presentations. A conditioned emotional response was established to the light in both groups. Finally, generalization tests of this response were conducted. Only the group that received sensory preconditioning exhibited transfer of the conditioned emotional response.