A novel approach to mechanical foot stimulation during human locomotion under body weight support

Input from the foot plays an essential part in perceiving support surfaces and determining kinematic events in human walking. To simulate adequate tactile pressure inputs under body weight support (BWS) conditions that represent an effective form of locomotion training, we here developed a new method of phasic mechanical foot stimulation using light-weight pneumatic insoles placed inside the shoes (under the heel and metatarsus). To test the system, we asked healthy participants to walk on a treadmill with different levels of BWS. The pressure under the stimulated areas of the feet and subjective sensations were higher at high levels of BWS and when applied to the ball and toes rather than heels. Foot stimulation did not disturb significantly the normal motor pattern, and in all participants we evoked a reliable step-synchronized triggering of stimuli for each leg separately. This approach has been performed in a general framework looking for “afferent templates” of human locomotion that could be used for functional sensory stimulation. The proposed technique can be used to imitate or partially restore surrogate contact forces under body weight support conditions.     

But for the bad, there would not be good: Grounding valence in brightness through shared relational structures

Light and dark are used pervasively to represent positive and negative concepts. Recent studies suggest that black and white stimuli are automatically associated with negativity and positivity. However, structural factors in experimental designs, such as the shared opposition in the valence (good vs. bad) and brightness (light vs. dark) dimensions might play an important role in the valence-brightness association. In 6 experiments, we show that while black ideographs are consistently judged to represent negative words, white ideographs represent positivity only when the negativity of black is coactivated. The positivity of white emerged only when brightness and valence were manipulated within participants (but not between participants) or when the negativity of black was perceptually activated by presenting positive and white stimuli against a black (vs. gray) background. These findings add to an emerging literature on how structural overlap between dimensions creates associations and highlight the inherently contextualized construction of meaning structures.     

Reciprocity: weak or strong? What punishment experiments do (and do not) demonstrate

Economists and biologists have proposed a distinction between two mechanisms--"strong" and "weak" reciprocity--that may explain the evolution of human sociality. Weak reciprocity theorists emphasize the benefits of long-term cooperation and the use of low-cost strategies to deter free-riders. Strong reciprocity theorists, in contrast, claim that cooperation in social dilemma games can be sustained by costly punishment mechanisms, even in one-shot and finitely repeated games. To support this claim, they have generated a large body of evidence concerning the willingness of experimental subjects to punish uncooperative free-riders at a cost to themselves. In this article, I distinguish between a "narrow" and a "wide" reading of the experimental evidence. Under the narrow reading, punishment experiments are just useful devices to measure psychological propensities in controlled laboratory conditions. Under the wide reading, they replicate a mechanism that supports cooperation also in "real-world" situations outside the laboratory. I argue that the wide interpretation must be tested using a combination of laboratory data and evidence about cooperation "in the wild." In spite of some often-repeated claims, there is no evidence that cooperation in the small egalitarian societies studied by anthropologists is enforced by means of costly punishment. Moreover, studies by economic and social historians show that social dilemmas in the wild are typically solved by institutions that coordinate punishment, reduce its cost, and extend the horizon of cooperation. The lack of field evidence for costly punishment suggests important constraints about what forms of cooperation can or cannot be sustained by means of decentralised policing.     

The role of kinematic mental simulation in creating false memories

Our investigation focuses on memory for scenes depicted in photos. According to the mental model theory, the observation of a static scene depicted in a photo which portrays an actor near to perform an action can trigger a kinematic mental simulation of that action unfolding in time. The deriving prediction is that such a kinematic mental model supports the creation of a false memory of the actor performing an advanced phase of the action. We test this prediction in three experiments in which participants are presented with static scenes of actions, and after three days they perform a recognition task in which they assess recognition of old and novel static scenes depicting actions. The results confirm that false memories occur for actions that represent the unfolding over time of the static action initially observed. Our theoretical framework can accommodate also several previous findings in the literature on false memories.     

Small-sample characterization of stochastic approximation staircases in forced-choice adaptive threshold estimation

Despite the widespread use of up-down staircases in adaptive threshold estimation, their efficiency and usability in forced-choice experiments has been recently debated. In this study, simulation techniques were used to determine the small-sample convergence properties of stochastic approximation (SA) staircases as a function of several experimental parameters. We found that satisfying some general requirements (use of the accelerated SA algorithm, clear suprathreshold initial stimulus intensity, large initial step size) the convergence was accurate independently of the spread of the underlying psychometric function. SA staircases were also reliable for targeting percent-correct levels far from the midpoint of the psychometric function and performed better than classical up-down staircases with fixed step size. These results prompt the utilization of SA staircases in practical forced-choice estimation of sensory thresholds.     

Off the beaten track: Freud,sound and music.Statement of a problem and some historico‐critical notes1

The authors note that the element of sound and music has no place in the model of mental functioning bequeathed to us by Freud, which is dominated by the visual and the representational. They consider the reasons for this exclusion and its consequences, and ask whether the simple biographical explanation offered by Freud himself is acceptable. This contribution reconstructs the historical and cultural background to that exclusion, cites some relevant emblematic passages, and discusses Freud’s position on music and on the aesthetic experience in general. Particular attention is devoted to the relationship between Freud and Lipps, which is important both for the originality of Lipps’s thinking in the turn‐of‐the‐century debate and for his ideas on the musical aspects of the foundations of psychic life, at which Freud ‘stopped’, as he himself wrote. Moreover, the shade of Lipps accompanied Freud throughout his scientific career from 1898 to 1938. Like all foundations, that of psychoanalysis was shaped by a system of inclusions and exclusions. The exclusion of the element of sound and music is understandable in view of the cultural background to the development of the concepts of the representational unconscious and infantile sexuality. While the consequences have been far reaching, the knowledge accumulated since that exclusion enables us to resume, albeit on a different basis, the composition of the ‘unfinished symphony’ of the relationship between psychoanalysis and music.     

A modified mark test for own-body recognition in pig-tailed macaques (Macaca nemestrina)

Classic mirror self-recognition mark tests involve familiarizing the subject with its mirror image, surreptitiously applying a mark on the subject’s eyebrow, nose, or ear, and measuring self-directed behaviors toward the mark. For many non-human primate species, however, direct gaze at the face constitutes an aggressive and threatening signal. It is therefore possible that monkeys fail the mark test because they do not closely inspect their faces in a mirror and hence they have no expectations about their physical appearance. In the current study, we prevented two pig-tailed macaques (Macaca nemestrina) from seeing their own faces in a mirror, and we adopted a modified version of the classic mark test in which monkeys were marked on the chest, a body region to which they normally have direct visual access but that in the current study was visible only via a mirror. Neither monkey tried to touch the mark on its chest, possibly due to a failure to understand the mirror as a reflective surface. To further the monkeys’ understanding of the mirror image, we trained them to reach for food using the mirror as the only source of information. After both monkeys had learned mirror-mediated reaching, we replicated the mark test. In this latter phase of the study, only one monkey scratched the red dye on the chest once. The results are consistent with other findings suggesting that monkeys are not capable of passing a mark test and imply that face and body recognition rely on the same cognitive abilities.     

Am I guilty or not? Deontological guilt,uncertainty, and checking behavior

Literature suggests that checking behaviors are aimed at reducing feelings of uncertainty both in clinical samples with obsessive‐compulsive disorder and in general population. Previous studies also showed that deontological guilt is an emotion often associated with obsessive‐compulsive disorder. Thus, the aim of the current study was to investigate the differences in checking behaviors in the condition of high versus low uncertainty, by exploring the moderating role of deontological versus altruistic guilt. Participants were 108 undergraduate Italian university students who took part in a visual search task designed to elicit checking behavior. Ahead of the visual task, participants were administered one scenario in order to manipulate either deontological or altruistic guilt. The results showed that in the condition of uncertainty, compared with the condition of certainty, participants spent more time in checking behaviors and that such a difference was more consistent when participants experienced deontological rather than altruistic guilt. Limitations and further directions are discussed.