Conditioned placebo responses

Following earlier animal research, we attempt to condition placebo effects in human subjects. Four groups of 8 voluntary subjects were told that the experimenters would test a powerful new analgesic cream over three sessions by assessing its ability to reduce experimentally induced pain. The analgesic cream was, in fact, a placebo. In the first session all subjects were tested with and without the cream to assess their placebo response. In the second session, to condition two groups (with differing stimulation levels) to experience pain relief in response to the placebo, we repeatedly paired a reduction in nocioceptive stimulation with placebo administration. (Subjects were unaware that stimulation levels were manipulated). To condition the other two groups (with different stimulation levels) to experience an exacerbation of the pain, we paired an increase in nocioceptive stimulation with placebo administration. In the third session, all subjects were again tested for placebo response. Results suggested that placebo responses are conditionable in the laboratory in both a positive and negative direction. The clinical implications of a learning theory of placebo behavior are discussed.     

The Depressive Experiences Questionnaire: revision and validation

The present study presents a new, unit-weight scoring system for the Depressive Experiences Questionnaire (DEQ). One hundred thirty-one college students completed the DEQ, the Bem Sex-Role Inventory (BSRI), and the Beck Depression Inventory (BDI). The revised DEQ scales were shown to have substantial levels of internal consistency. The three subscales of the revised DEQ were significantly correlated with the BSRI masculinity and femininity scales but not with gender. Significant correlations were also obtained between DEQ anaclitic, DEQ introjective scales and the BDI.     

Squeezing, striking, and vocalizing: Is number representation fundamentally spatial?

Numbers are fundamental entities in mathematics, but their cognitive bases are unclear. Abundant research points to linear space as a natural grounding for number representation. But, is number representation fundamentally spatial? We disentangle number representation from standard number-to-line reporting methods, and compare numerical estimations in educated participants using line-reporting with three nonspatial reporting conditions (squeezing, bell-striking, and vocalizing). All three cases of nonspatial-reporting consistently reproduced well-established results obtained with number-line methods. Furthermore, unlike line-reporting—and congruent with the psychophysical Weber–Fechner law—nonspatial reporting systematically produced logarithmic mappings for all nonsymbolic stimuli. Strikingly, linear mappings were obtained exclusively in conditions with culturally mediated elements (e.g., words). These results suggest that number representation is not fundamentally spatial, but builds on a deeper magnitude sense that manifests spatially and nonspatially mediated by magnitude, stimulus modality, and reporting condition. Number-to-space mappings—although ubiquitous in the modern world—do not seem to be rooted directly in brain evolution but have been culturally privileged and enhanced.     

Only self-generated actions create sensori-motor systems in the developing brain

Previous research shows that sensory and motor systems interact during perception, but how these connections among systems are created during development is unknown. The current work exposes young children to novel 'verbs' and objects through either (a) actively exploring the objects or (b) by seeing an experimenter interact with the objects. Results demonstrate that the motor system is recruited during auditory perception only after learning involved self-generated interactions with objects. Action observation itself led to above-baseline activation in one motor region during visual perception, but was still significantly less active than after self-generated action. Therefore, in the developing brain, associations are built upon real-world interactions of body and environment, leading to sensori-motor representations of both objects and words.     

Distinguishing multi-voxel patterns and mean activation: Why, how, and what does it tell us?

The introduction of multi-voxel pattern analysis (MVPA) to the functional magnetic resonance imaging (fMRI) community has brought a deeper appreciation for the diverse forms of information that can be present within fMRI activity. The conclusions drawn from MVPA investigations are frequently influenced by both the ability to decode information from multi-voxel patterns and mean activation levels. In practice, MVPA studies vary widely in why and how they test for differing overall response levels. In this article, I examine the place of univariate information in MVPA investigations. I first discuss the variety of interpretations given to finding univariate response differences. I go on to discuss some of the analysis approaches used to investigate and compare univariate and multivariate sources of information, which can illuminate their respective contributions. It will be important for the MVPA and general fMRI community to continue to discuss and debate these important issues.     

Individual differences in spatial configuration learning predict the occurrence of intrusive memories

The dual-representation model of posttraumatic stress disorder (PTSD; Brewin, Gregory, Lipton, & Burgess, Psychological Review, 117, 210-232 2010) argues that intrusions occur when people fail to construct context-based representations during adverse experiences. The present study tested a specific prediction flowing from this model. In particular, we investigated whether the efficiency of temporal-lobe-based spatial configuration learning would account for individual differences in intrusive experiences and physiological reactivity in the laboratory. Participants (N = 82) completed the contextual cuing paradigm, which assesses spatial configuration learning that is believed to depend on associative encoding in the parahippocampus. They were then shown a trauma film. Afterward, startle responses were quantified during presentation of trauma reminder pictures versus unrelated neutral and emotional pictures. PTSD symptoms were recorded in the week following participation. Better configuration learning performance was associated with fewer perceptual intrusions, r = ?.33, p < .01, but was unrelated to physiological responses to trauma reminder images (ps > .46) and had no direct effect on intrusion-related distress and overall PTSD symptoms, rs > ?.12, ps > .29. However, configuration learning performance tended to be associated with reduced physiological responses to unrelated negative images, r = ?.20, p = .07. Thus, while spatial configuration learning appears to be unrelated to affective responding to trauma reminders, our overall findings support the idea that the context-based memory system helps to reduce intrusions.