Generalization of appetitive conditioned responses

Abstract

A stimulus (conditioned stimulus, CS) associated with an appetitive unconditioned stimulus (US) acquires positive properties and elicits appetitive conditioned responses (CR). Such associative learning has been examined extensively in animals with food as the US, and results are used to explain psychopathologies (e.g., substance‐related disorders or obesity). Human studies on appetitive conditioning exist, too, but we still know little about generalization processes. Understanding these processes may explain why stimuli not associated with a drug, for instance, can elicit craving. Forty‐seven hungry participants underwent an appetitive conditioning protocol during which one of two circles with different diameters (CS+) became associated with an appetitive US (chocolate or salty pretzel, according to participants’ preference) but never the other circle (CS−). During generalization, US were delivered twice and the two CS were presented again plus four circles (generalization stimuli, GS) with gradually increasing diameters from CS− to CS+. We found successful appetitive conditioning as reflected in appetitive subjective ratings (positive valence, higher contingency) and physiological responses (startle attenuation and larger skin conductance responses) to CS+ versus CS−, and, importantly, both measures confirmed generalization as indicated by generalization gradients. Small changes in CS‐US contingency during generalization may have weakened generalization processes on the physiological level. Considering that appetitive conditioned responses can be generalized to non‐US‐associated stimuli, a next important step would be to investigate risk factors that mediate overgeneralization.

Generalization of Conditioned Contextual Anxiety and the Modulatory Effects of Anxiety Sensitivity

“…Moreover, the verbal conditioned responses demonstrated that the G75-CTX and the G50-CTX were more anxiogenic than the CTX−, whereas the G25-CXT was rated as safe as the safety context. These results replicate previous findings [36][37][38][39] indicating that the generalization context with equal properties of anxiety and safety context was reported as threatening. Furthermore, we could extend these results as well as results on fear generalization [18][19][20]22] by showing that the Fig.…”

“…Conceivably, high anxiety sensitive individuals would have shown both a linear generalization trend and startle potentiation to the generalization contexts as compared to the safety context. Although simple contrasts for physiological responses between generalization contexts and safety context is in contrast to the verbal reports, it is in line with previous studies in which the physiological conditioned anxiety was not generalized to the G50-CTX [36][37][38][39]. Notably, such safety generalization is also evident in the literature of cue conditioning, in which it has been found that the equal mix of the threat and safety signal does not elicit strong fear responses in healthy individuals [18][19][20]22].…”

“…The pictures depicted the same forest, but during different seasons so that they shared some properties, but differed in others. Interestingly and in line with our studies [37][38][39], the authors found generalization of conditioned anxiety on the verbal level (i.e., ratings for the expectancy of the US), but not on the physiological level (i.e., startle response).…”

“…Conceivably, conditioned contextual anxiety may become generalized as cued fear; however, this is much less investigated [15][16][17]36]. To overcome this lack, we extended the abovementioned VR-context conditioning paradigm and examined anxiety responses to the anxiety and safety contexts plus to an additional virtual office, which was an equal mix of the anxiety and the safety context [37][38][39]. Interestingly, we found a dissociation between the verbal and the physiological responses of healthy individuals, i.e., they rated the generalization context (G-CTX) as aversive as the anxiety context but exhibited startle responses as in the safety context.…”

Semantic generalization of value-based attentional priority

“…Peelen (2015, 2017) also reported a generalization of associations between naturalistic visual stimuli and reward to objects of the same category (e.g., cars). More recently, Andreatta and Pauli (2019) showed that appetitive conditioned responses transferred to stimuli perceptually related to signals paired with food consumption in a prior acquisition phase. However, studies about the generalization of stimulus-reward associations mainly focused on perceptual cues.…”