Beyond awareness and resources: Evaluative conditioning may be sensitive to processing goals

Evaluative conditioning (EC) is often regarded as an automatic affective learning process. Yet, recent empirical evidence suggests that EC may actually be sensitive to contingency awareness and to the availability of attentional resources. Here, we examine for the first time a third horseman of EC automaticity: processing goals. Specifically, we had participants engage an EC task after completing a task known to elicit the goal of processing either the perceptual similarities or the perceptual differences between stimuli. EC was predicted and found to be larger in the former (similarity-focus) than in the latter (difference-focus) condition. This finding provides original evidence that EC is sensitive to the processing goal activated in participants as they encode the CS-US pairings. The theoretical implications of this finding are discussed.     

Learning strategies during fear conditioning

This paper describes a model of fear learning, in which subjects have an option of behavioral responses to impending social defeat. The model generates two types of learning: social avoidance and classical conditioning, dependent upon (1) escape from or (2) social subordination to an aggressor. We hypothesized that social stress provides the impetus as well as the necessary information to stimulate dichotomous goal-oriented learning. Specialized tanks were constructed to subject rainbow trout to a conditioning paradigm where the conditioned stimulus (CS) is cessation of tank water flow (water off) and the unconditioned stimulus (US) is social aggression from a larger conspecific. Following seven daily CS/US pairings, approximately half of the test fish learned to consistently escape the aggression to a neutral chamber through a small escape hole available only during the interaction. The learning curve for escaping fish was dramatic, with an 1100% improvement in escape time over 7 days. Fish that did not escape exhibited a 400% increase in plasma cortisol and altered brain monoamine response to presentation of the CS alone. Elevated plasma cortisol levels represent classical fear conditioning in non-escaping fish, while a lack of fear conditioning and a decreased latency to escape over the training period in escapers indicates learned escape.     

Evidence for associative learning in newly emerged honey bees (Apis mellifera)

The honey bee is a model organism for studies on the neural substrates of learning and memory. Associative olfactory learning using sucrose rewards is fast and reliable in foragers and older hive bees. However, researchers have so far failed to show any significant learning in newly emerged bees. It is generally argued that in these bees only part of the brain structures important for learning are fully developed. Here we show for the first time that newly emerged honey bees are capable of associative learning, if they are sufficiently responsive to sucrose. Responsiveness to sucrose, which can be measured using the proboscis extension response (PER), increases with age. Newly emerged bees are on average very unresponsive to sucrose. We show that if newly emerged bees displaying a PER to 10% sucrose or lower sucrose concentrations are conditioned to an odour, they show significant associative learning and early long-term memory. Nevertheless, the level of acquisition is still lower than in foragers. The general assumption that newly emerged honey bees are incapable of associative learning must therefore be reconsidered. Further, our study suggests that an age-dependent increase in responsiveness to rewarding stimuli is directly related to the development of early learning abilities. The decisive influence of responsiveness to rewarding stimuli in associative learning of newly emerged bees has far reaching consequences for studies on the development of associative learning capabilities in insects and vertebrates.     

Fearing shades of grey: individual differences in fear responding towards generalisation stimuli

Individual differences in fear generalisation have been proposed to play a role in the aetiology and/or maintenance of anxiety disorders, but few data are available to directly support that claim. The research that is available has focused mostly on generalisation of peripheral and central physiological fear responses. Far less is known about the generalisation of avoidance, the behavioural component of fear. In two experiments, we evaluated how neuroticism, a known vulnerability factor for anxiety, modulates an array of fear responses, including avoidance tendencies, towards generalisation stimuli (GS). Participants underwent differential fear conditioning, in which one conditioned stimulus (CS+) was repeatedly paired with an aversive outcome (shock; unconditioned stimulus, US), whereas another was not (CS?). Fear generalisation was observed across measures in Experiment 1 (US expectancy and evaluative ratings) and Experiment 2 (US expectancy, evaluative ratings, skin conductance, startle responses, safety behaviours), with overall highest responding to the CS+, lowest to the CS? and intermediate responding to the GSs. Neuroticism had very little impact on fear generalisation (but did affect GS recognition rates in Experiment 1), in line with the idea that fear generalisation is largely an adaptive process.     

Associative learning versus fear habituation as predictors of long-term extinction retention

Violation of unconditioned stimulus (US) expectancy during extinction training may enhance associative learning and result in improved long-term extinction retention compared to within-session habituation. This experiment examines variation in US expectancy (i.e., expectancy violation) as a predictor of long-term extinction retention. It also examines within-session habituation of fear-potentiated startle (electromyography, EMG) and fear of conditioned stimuli (CS) throughout extinction training as predictors of extinction retention. Participants (n?=?63) underwent fear conditioning, extinction and retention and provided continuous ratings of US expectancy and EMG, as well as CS fear ratings before and after each phase. Variation in US expectancy throughout extinction and habituation of EMG and fear was entered into a regression as predictors of retention and reinstatement of levels of expectancy and fear. Greater variation in US expectancy throughout extinction training was significantly predictive of enhanced extinction performance measured at retention test, although not after reinstatement test. Slope of EMG and CS fear during extinction did not predict retention of extinction. Within-session habituation of EMG and self-reported fear is not sufficient for long-term retention of extinction learning, and models emphasizing expectation violation may result in enhanced outcomes.     

Instructed fear learning,extinction, and recall: additive effects of cognitive information on emotional learning of fear

The effects of instruction on learning of fear and safety are rarely studied. We aimed to examine the effects of cognitive information and experience on fear learning. Fourty healthy participants, randomly assigned to three groups, went through fear conditioning, extinction learning, and extinction recall with two conditioned stimuli (CS+). Information was presented about the presence or absence of conditioned stimulus–unconditioned stimulus (CS–US) contingency at different stages of the experiment. Information about the CS–US contingency prior to fear conditioning enhanced fear response and reduced extinction recall. Information about the absence of CS–US contingency promoted extinction learning and recall, while omission of this information prior to recall resulted in fear renewal. These findings indicate that contingency information can facilitate fear expression during fear learning, and can facilitate extinction learning and recall. Information seems to function as an element of the larger context in which conditioning occurs.     

Ignorance reflects preference: the influence of selective ignoring on evaluative conditioning

In the current experiment, we investigated the mechanism underlying the modulation of evaluative conditioning (EC) due to selective attention. Conditioned stimulus–unconditioned stimulus (CS–US) pairs were presented in a just recently introduced adapted Flanker paradigm [Blask, K., Walther, E., & Frings, C. (2016). When congruence breeds preference: The influence of selective attention processes on evaluative conditioning. Cognition and Emotion. doi:10.1080/02699931.2016.1197100] with CSs as targets and USs as task-irrelevant distracters. In order to disentangle stimulus congruency and response compatibility and in order to observe a possible impact of response compatibility, EC in an incongruent/incompatible condition was compared to EC in an incongruent/neutral condition. Results show that EC and contingency memorywere significantly reduced in the incongruent/incompatible condition relative to the incongruent/neutral condition. These findings support the notion that the modulation of EC due to selective attention can be based on the selective ignoring of the US at the level of response compatibility.     

条件反射性免疫抑制研究的新进展

条件反射性免疫抑制 (CIS)模式基于巴甫洛夫条件反射的机理 ,通过大脑对免疫系统进行调节 ,是一种重要的心理神经免疫学方法。近 10年来的研究取得了一些重要的进展。首先 ,条件反射性免疫抑制模型已证实是非常稳定可靠的心理神经免疫模型。其次 ,关于CIS的机制在体液、细胞、神经学方面都有广泛的研究 ,而近年来更趋向于对神经性通路的探讨。而CIS的临床应用性研究也在实验动物身上取得了稳定可靠的结果 ,证实了其未来临床应用的可行性及潜力     

Conducting extinction in multiple contexts does not necessarily attenuate the renewal of shock expectancy in a fear-conditioning procedure with humans

The renewal of Pavlovian-conditioned responses may provide a model for the relapse of fear following extinction-based treatments for anxiety disorders. Renewal can be observed if conditional stimulus (CS) and unconditional stimulus (US) pairings are given in one context, extinction trials of CS presentations in a second context, prior to test trials of CS presentations in the original acquisition context (ABA renewal). We examined ABA renewal in humans by using a fear-conditioning procedure with an unpleasant shock US. A renewal of rated shock expectancy was demonstrated with this procedure. Conducting extinction treatment in multiple contexts was expected to attenuate the renewal effect. However, the renewal of shock expectancy persisted when extinction treatment was given across three or five different contexts. With the current renewal design, learning task, and measure of conditioned behaviour, extinction treatment does not appear to readily generalise to the test context. The use of multiple extinction treatments in a clinical setting may not necessarily reduce the likelihood of relapse via a renewal effect.     

The effects of context extinction on US signal value

Two experiments with rats examined the effects of context extinction on responding to the signal value of an unconditioned stimulus (US). In Experiment 1, US signal value was first trained when a single food pellet signaled the delivery of three additional pellets. After training, rats received either context extinction (CE) or home cage (HC) exposure before testing US signal value by single food pellet presentations. Results showed responding was significantly reduced in Group CE compared to Group HC. Experiment 2 replicated Experiment 1 and showed that exposure to a different context did not reduce responding to the signal value of a US. The results complement research by Kehoe et al. [Kehoe, E. J., Weidemann, G., & Dartnall, S. (2004). Apparatus exposure produces profound declines in conditioned nictitating-membrane responses to discrete conditioned stimuli by the rabbit (Oryctolagus cuniculus). Journal of Experimental Psychology: Animal Behavior Processes, 30, 259–270.] and have key implications for prominent theories of conditioning.