Can human autonomic classical conditioning occur without contingency awareness? The critical importance of the trial sequence

Rating expectations can slow aversive reversal learning

The process of learning allows organisms to develop predictions about outcomes in the environment, and learning is sensitive to both simple associations and higher order knowledge. However, it is unknown whether consciously attending to expectations shapes the learning process itself. Here, we directly tested whether rating expectations shapes arousal during classical conditioning. Participants performed an aversive learning paradigm wherein one image (CS+) was paired with shock on 50% of trials, while a second image (CS-) was never paired with shock. Halfway through the task, contingencies reversed. One group of participants rated the probability of upcoming shock on each trial, while the other group made no online ratings. We measured skin conductance response (SCR) evoked in response to the CS and used traditional analyses as well as quantitative models of reinforcement learning to test whether rating expectations influenced arousal and aversive reversal learning. Participants who provided online expectancy ratings displayed slower learning based on a hybrid model of adaptive learning and reduced reversal of SCR relative to those who did not rate expectations. Mediation analysis revealed that the effect of associative learning on SCR could be fully explained through its effects on subjective expectancy within the group who provided ratings. This suggests that the act of rating expectations reduces the speed of learning, likely through changes in attention, and that expectations directly influence arousal. Our findings indicate that higher order expectancy judgments can alter associative learning.

Conceptual fear generalization gradients and their relationship with anxious traits: Results from a Registered Report

A hallmark symptom of fear and anxiety disorder is generalization of fear to essentially innocuous stimuli and situations. Such generalization can occur through both perceptual and conceptually similarities. Recent studies indicate that perceptual generalization is inflated in anxiety patients and individuals prone to develop anxiety disorders, suggesting that perceptual generalization may be involved in the etiology of anxiety disorders. In the current Registered Report, we wanted to address whether conceptual generalization is potentially implicated in the development of anxiety disorders as well. Therefore, we used a novel paradigm in which the Dutch word mini [tiny] or enorm [enormous] was paired with an electric shock and assessed fear to the conceptually related words klein [small], medium [medium], and groot [large]. The sample (N = 120) consisted of healthy university students. As hypothesized, we observed clear conceptual fear generalization gradients using both self-report and psychophysiological measures. However, in contrast to our expectations, these conceptual generalization gradients were not correlated with different anxious traits (i.e., trait anxiety, intolerance of uncertainty, and behavioral inhibition). These results show that fear can generalize conceptually along a gradient, without requiring perceptual errors as postulated by traditional models of fear generalization. Instead, our results correspond well with inferential reasoning theories of fear generalization. Additionally, we discuss potential reasons for the absence of the expected correlations between conceptual fear generalization and anxious traits, such as restricted variability in both the generalization task and the sample. We conclude that the paradigm has promise for further research on conceptual fear generalization.

Concurrent Electrodermal and Eyeblink Conditioning With Masked and Unmasked Stimuli

Abstract. The aim of this study was to determine if contingency awareness between the conditioned (CS) and unconditioned stimulus (US) is necessary for concurrent electrodermal and eyeblink conditioning to masked stimuli. An angry woman’s face (CS+) and a fearful face (CS−) were presented for 23 milliseconds (ms) and followed by a neutral face as a mask. A 98 dB noise burst (US) was administered 477 ms after CS+ offset to elicit both electrodermal and eyeblink responses. For the unmasking conditioning a 176 ms blank screen was inserted between the CS and the mask. Contingency awareness was assessed using trial-by-trial ratings of US-expectancy in a post-conditioning phase. The results showed acquisition of differential electrodermal and eyeblink conditioning in aware, but not in unaware participants. Acquisition of differential eyeblink conditioning required more trials than electrodermal conditioning. These results provided strong evidence of the causal role of contingency awareness on differential eyeblink and electrodermal conditioning.

Human fear conditioning is moderated by stimulus contingency instructions

Recent research findings indicate that human fear conditioning is affected by instructions, particularly those concerning the contingency between the conditioned stimulus (CS) and the unconditioned stimulus (US). However, whether or not such instructions were provided to participants often remains unsaid in fear conditioning studies. In the current study (N = 102), we investigated whether conditioned fear acquisition depends on CS-US contingency instructions. Participants were randomly assigned to one of three groups. The first group was instructed about the precise CS-US contingency before conditioning. The second group was instructed to discover the CS-US contingency. The third group did not receive any contingency instructions. We found facilitated fear acquisition (using skin conductance and startle) and increased contingency awareness in the first and second group compared to the third group. Furthermore, contingency reversal instructions immediately reversed conditioned responses. Based on these results, we advise to systematically report the contingency instructions used in fear conditioning research.

Awareness and differential eyeblink conditioning: effects of manipulating auditory CS frequencies

The role of awareness in differential delay eyeblink conditioning (EBC) has been a topic of much debate. We tested the idea that awareness is required for differential delay EBC when two cues are perceptually similar. The present study manipulated frequencies of auditory conditioned stimuli (CS) to vary CS similarity in three groups of participants. Our findings indicate that awareness was not necessary for differential delay EBC when two tones are easily discriminable, awareness was also not needed for relatively similar tones but may facilitate earlier conditioning, and awareness alone was not sufficient for differential delay EBC.

The role of US recency in the Perruchet effect in eyeblink conditioning

In the Perruchet effect, there is a concurrent dissociation between participants' conditioned responses (CRs) and their expectancy of the unconditioned stimulus (US) across runs of repeated trials. The effect has been taken as evidence for multiple learning processes, but this conclusion follows only if the CR trend is the result of learning. Two experiments examined the role of US recency in generating the observed CR trend. A standard Perruchet condition was compared with a control condition in which US recency was controlled by presenting the US on every trial. The associative contribution was maintained by varying the temporal relationship between the CS and the US. In both experiments the pattern of CRs seen in the Perruchet condition was absent in the control condition, suggesting that the eyeblink trend in the Perruchet effect may be due to a non-associative performance factor such as priming or sensitization arising from recent US presentations.

Eye Movements Index Implicit Memory Expression in Fear Conditioning

The role of contingency awareness in simple associative learning experiments with human participants is currently debated. Since prior work suggests that eye movements can index mnemonic processes that occur without awareness, we used eye tracking to better understand the role of awareness in learning aversive Pavlovian conditioning. A complex real-world scene containing four embedded household items was presented to participants while skin conductance, eye movements, and pupil size were recorded. One item embedded in the scene served as the conditional stimulus (CS). One exemplar of that item (e.g. a white pot) was paired with shock 100 percent of the time (CS+) while a second exemplar (e.g. a gray pot) was never paired with shock (CS-). The remaining items were paired with shock on half of the trials. Participants rated their expectation of receiving a shock during each trial, and these expectancy ratings were used to identify when (i.e. on what trial) each participant became aware of the programmed contingencies. Disproportionate viewing of the CS was found both before and after explicit contingency awareness, and patterns of viewing distinguished the CS+ from the CS-. These observations are consistent with "dual process" models of fear conditioning, as they indicate that learning can be expressed in patterns of viewing prior to explicit contingency awareness.

Fear conditioning of SCR but not the startle reflex requires conscious discrimination of threat and safety

There is conflicting evidence as to whether awareness is required for conditioning of the skin conductance response (SCR). Recently, Schultz and Helmstetter (2010) reported SCR conditioning in contingency unaware participants by using difficult to discriminate stimuli. These findings are in stark contrast with other observations in human fear conditioning research, showing that SCR predominantly reflects contingency learning. Therefore, we repeated the study by Schultz and Helmstetter and additionally measured conditioning of the startle response, which seems to be less sensitive to declarative knowledge than SCR. While we solely observed SCR conditioning in participants who reported awareness of the contingencies (n = 16) and not in the unaware participants (n = 18), we observed startle conditioning irrespective of awareness. We conclude that SCR but not startle conditioning depends on conscious discriminative fear learning.

Can you give me a hand? A comparison of hands and feet as optimal anatomical sites for skin conductance recording

The fingers and feet have long been accepted as optimal anatomical recording sites for electrodermal activity. The available literature suggests that the feet are more responsive than the fingers. The present report compared skin conductance level (SCL) and responses (SCRs) from the left foot and the distal phalanges of the fingers on the nondominant hand among 19 participants. The principal results were (a) SCRs recorded from the fingers were significantly larger and more frequent with shorter latencies than SCRs from the foot, (b) SCL from the fingers was significantly higher than from the foot, (c) the fingers exhibited significantly greater discrimination conditioning than the foot, and (d) skin conductance measures recorded from the fingers and foot were significantly positively correlated. Specifically, our results demonstrate that the distal phalanges of the fingers are electrodermally more responsive than the abductor hallucis area of the foot.