Illusory line motion and transformational apparent motion during continuous flash suppression1

A static bar is perceived to dynamically extend from a peripheral cue (illusory line motion (ILM)) or from a part of another figure presented in the previous frame (transformational apparent motion (TAM)). We examined whether visibility for the cue stimuli affected these transformational motions. Continuous flash suppression, one kind of dynamic interocular masking, was used to reduce the visibility for the cue stimuli. Both ILM and TAM significantly occurred when the d' for cue stimuli was zero (Experiment 1) and when the cue stimuli were presented at subthreshold levels (Experiment 2). We discuss that higher‐order motion processing underlying TAM and ILM can be weakly but significantly activated by invisible visual information.     

The moving rubber hand illusion revisited: Comparing movements and visuotactile stimulation to induce illusory ownership

The rubber hand illusion is a perceptual illusion in which a model hand is experienced as part of one’s own body. In the present study we directly compared the classical illusion, based on visuotactile stimulation, with a rubber hand illusion based on active and passive movements. We examined the question of which combinations of sensory and motor cues are the most potent in inducing the illusion by subjective ratings and an objective measure (proprioceptive drift). In particular, we were interested in whether the combination of afferent and efferent signals in active movements results in the same illusion as in the purely passive modes. Our results show that the illusion is equally strong in all three cases. This demonstrates that different combinations of sensory input can lead to a very similar phenomenological experience and indicates that the illusion can be induced by any combination of multisensory information.     

The use of realistic and mechanical hands in the rubber hand illusion,and the relationship to hemispheric differences

Embodiment, as measured through the rubber-hand illusion (RHI), depends on the similarity between object to be embodied and part of the body it replaces. We compared a fake hand similar to a real hand, and one matched in size but made of wires (mechanical). Left and right versions were tested to investigate whether the effect of appearance was stronger in the left hand. We found that the mechanical hand induced embodiment, though to a reduced degree relative to the realistic hand (N = 120). Left and right versions of the mechanical hand did not differ in strength of the illusion. However, with the left realistic hand there was a stronger relationship between drift (an objective measure of the illusion) and agreement on the questionnaire (subjective experience). With the mechanical hand, objective and subjective measures were unrelated. We discuss the results in relation to factors that influence the RHI and hemispheric differences.     

Extinction in human learning and memory

In two experiments, participants were given extinction training in a human causal learning task. In both experiments, three critical experimental cues were paired with different outcomes in a first phase of training and were then extinguished in a second phase. Three control cues were given the same treatment in the first phase of training, but were not then presented in the second phase. Participants' ability to correctly identify the outcome with which each cue had been paired in the first phase was lower for extinguished than for control cues. Causal attributions to the extinguished cues were also lower than those to the control cues, a difference that correlated with outcome memory. These data are consistent with the idea that extinction in causal judgement is due, at least in part, to a failure to remember the cue–outcome relationship encoded in the first phase of training.     

Acquisition of a conditioned taste aversion becomes context dependent when it is learned after extinction

A conditioned taste aversion experiment tested context-switch effects on retrieval of conditioned stimulus (CS)–unconditioned stimulus (US) acquisition performance in rats. A context switch impaired performance when the target flavour was trained in a context where a different flavour underwent extinction. Conditioned taste aversion in the absence of previous extinction of the alternate flavour was not context dependent. It is suggested that the ambiguity in the meaning of the extinguished cue leads animals to pay attention to the context, so that the information learned in that context becomes context dependent.     

Independent effects of emotion and attention on sensory and affective pain perception

The present study investigated whether attention and emotion independently influence sensory and affective pain ratings. Fifty-four (27 female) participants rated sensory and affective pain in response to painful mechanic pressure stimulation while exposed to positive, neutral and negative slides from the International Affective Picture System. In doing so, participants were assigned to one of three groups, which focused attention either on the pictures or on the sensory or on the affective aspects of the pressure stimulation. Consistent with the motivational priming hypothesis, sensory and affective pain ratings were generally lower during exposure to positive compared to negative and neutral slides. In line with our assumptions, attention modulated sensory pain ratings with lowest ratings in the picture focusing group and highest in the affective pain focusing group. No attention effect for affective pain ratings and no interactions between emotional and attentional effects on pain perception were found.     

Memory and the Moses illusion: Failures to detect contradictions with stored knowledge yield negative memorial consequences

Although contradictions with stored knowledge are common in daily life, people often fail to notice them. For example, in the Moses illusion, participants fail to notice errors in questions such as “How many animals of each kind did Moses take on the Ark?” despite later showing knowledge that the Biblical reference is to Noah, not Moses. We examined whether error prevalence affected participants' ability to detect distortions in questions, and whether this in turn had memorial consequences. Many of the errors were overlooked, but participants were better able to catch them when they were more common. More generally, the failure to detect errors had negative memorial consequences, increasing the likelihood that the errors were used to answer later general knowledge questions. Methodological implications of this finding are discussed, as it suggests that typical analyses likely underestimate the size of the Moses illusion. Overall, answering distorted questions can yield errors in the knowledge base; most importantly, prior knowledge does not protect against these negative memorial consequences.     

On the costs and benefits of directing attention towards or away from threat-related stimuli: A classical conditioning experiment

In attentional bias modification programs, individuals are trained to attend away from threat in order to reduce emotional reactivity to stressful situations. However, attending towards threat is considered to be a prerequisite for fear reduction in other models of anxiety. We compared both views by manipulating attention towards or away from an acquired signal of threat. The strength of extinction and reacquisition was assessed with threat and US-expectancy ratings. We found more extinction in the attend towards threat group, compared to both the attend away from threat group and a control group in which attention was not manipulated. The results are in line with the Emotional Processing Theory and cognitive accounts of classical conditioning.     

Outcome-specific transfer between predictive and instrumental learning is unaffected by extinction but reversed by counterconditioning in human participants

Three experiments were conducted to explore the effects of different interference treatments upon outcome-specific transfer from predictive learning to instrumental responding. A computer game was designed in which participants had to defend Andalusia from navy and air-force attacks. Participants learned the relationship between two instrumental responses (two keys in a standard keyboard) and two different outcomes (destruction of the ships or destruction of the planes). Then, they learned to predict which of two different cues predicted either outcome. Finally, participants were allowed to give either of the two instrumental responses in the presence of each cue. Outcome-specific transfer was shown as a preference for the response that shared the outcome with the current cue. Extinction of the cue before the transfer test had no effect upon transfer, regardless of the level of extinction (Experiments 1-3). However, pairing the cue with the alternative outcome (counterconditioning) reversed the outcome-based transfer effect (Experiment 3). The implications of these results for the contents of extinction in human predictive learning are discussed.     

Unpaired shocks during extinction weaken the contextual renewal of a conditioned discrimination

Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this should augment breaking the contingency between the two stimuli. In a human conditioning experiment with on-line expectancy ratings and electrodermal responding as dependent variables, 32 participants were differentially conditioned to two neutral figures using electric shock. After a change of context, one group received normal extinction treatment whereas another group received explicitly unpaired presentations of the figures and shock. At test, the two figures were presented in the original context again. For both measures, only the group that received normal extinction showed renewal of the conditioned discrimination. These results suggest that unpaired shocks during extinction strengthen the extinction learning.