Unilaterally applied stimuli in a frequency discrimination task are represented bilaterally in primary somatosensory cortex

Psychophysical studies have shown that there is somatotopically organized interaction in tasks involving somatosensory memory. In order to test the hypothesis that the ipsilateral somatosensory cortex contributes to the psychophysically demonstrated interaction, neuromagnetic steady-state responses induced by vibro-tactile stimuli were investigated in a frequency discrimination task. Subjects were requested to indicate whether two stimuli (first and test stimulus) presented subsequently at the index finger of one hand differed with respect to frequency. An interference stimulus interpolated between both stimuli was applied at the little or the index finger of either the left or right hand. Results show that in the present memory task, bilateral activation was found mainly for the test stimulus although stimuli were applied uni-laterally. As revealed by dipole analysis, sources ipsilateral to the side of stimulation were predominantly located in primary somatosensory cortex

Concurrent use of somatotopic and external reference frames in a tactile mislocalization task

Localizing tactile stimuli on our body requires sensory information to be represented in multiple frames of reference along the sensory pathways. These reference frames include the representation of sensory information in skin coordinates, in which the spatial relationship of skin regions is maintained. The organization of the primary somatosensory cortex matches such somatotopic reference frame. In contrast, higher-order representations are based on external coordinates, in which body posture and gaze direction are taken into account in order to localise touch in other meaningful ways according to task demands. Dominance of one representation or the other, or the use of multiple representations with different weights, is thought to depend on contextual factors of cognitive and/or sensory origins. However, it is unclear under which situations a reference frame takes over another or when different reference frames are jointly used at the same time. The study of tactile mislocalizations at the fingers has shown a key role of the somatotopic frame of reference, both when touches are delivered unilaterally to a single hand, and when they are delivered bilaterally to both hands. Here, we took advantage of a well-established tactile mislocalization paradigm to investigate whether the reference frame used to integrate bilateral tactile stimuli can change as a function of the spatial relationship between the two hands. Specifically, supra-threshold interference stimuli were applied to the index or little fingers of the left hand 200 ms prior to the application of a test stimulus on a finger of the right hand. Crucially, different hands postures were adopted (uncrossed or crossed). Results show that introducing a change in hand-posture triggered the concurrent use of somatotopic and external reference frames when processing bilateral touch at the fingers. This demonstrates that both somatotopic and external reference frames can be concurrently used to localise tactile stimuli on the fingers

Peoples’ Views About the Acceptability of Executive Bonuses and Compensation Policies

International audienceWe applied a technique borrowed from the field of bioethics to test whether justice-related factors influence laypersons’ decisions concerning business ethics. In the first experiment, participants judged the acceptability of remuneration policies and in the second that of executive bonuses. In each study, participants judged a set of 36 situations. To create the scenarios, we varied (a) retributive justice—the amount of remuneration; (b) procedural justice—the clarity of the procedure that determined the remuneration; (c) distributive justice—the extent of the distribution of bonus payments amongst employees; and (d) restorative justice—a special compensation for hazardous working conditions or accidents at work. K-means clustering of all 36 judgments revealed four different personal positions in both experiments. One group of people readily accepted all situations. The other three groups’ judgments were mainly a function of distributive justice modulated in different ways by the context determined by the other variables. Furthermore, people conceive of distributive justice as categorical: Acceptability judgments only increase if companies give bonuses to all employees. Granting bonuses to a subset (i.e. mangers or executives) does not increase acceptability. Our results are useful for policy makers and provide business ethics researchers with a novel technique