Perceived force in fatiguing isometric contractions

An integrative approach emphasizing both psychological and physiological components in force perception has started to emerge in motor psychophysics. In this experiment, the relation between isometric force (produced by the elbow flexors~ and perceived force was examined over a range of forces maintained until maximal endurance. A contralateral-limb matching procedure in which subjects estimated the force of a sustained, constant force contraction by contracting their unfatigued arm at regular intervals was employed. A linear increase in perceived force was observed during the fatiguing contractions, the rate of which depended on the level of force exerted. The sensation of force at maximal endurance was also found to vary with the force exerted. Based on the similarity between these results and those derived from electromyographic studies, we propose that observers use the efferent input to the muscle in preference to its afferent responses in judging the force of muscular contractions.     

Type of motion in inverted self-motion perception induced by a foreground stimulus

Slowly moving foreground induces an illusory self-motion perception in the same direction as its motion direction (inverted vection). In this study, the effects of motion type of the foreground stimulus on inverted vection were investigated using a sample of 3 men and 1 woman. As indices of perceived strength of the inverted vection, duration and estimated magnitude were measured. Analysis of the psychophysical experiment indicated that a translating foreground induced inverted linear vection in the same direction as the stimulus motion. However, a rotating foreground did not induce an inverted roll vection. Statistical analyses indicate that there is a significant difference between two foreground motion conditions (Duration: t3=14.54, p <.01; Estimation: t3=16.92, p<.01). This result supports the hypothesis that eye-movement information is responsible for the occurrence of inverted vection.     

Liking products by the head of a dog: Perceived orientation of attention induces valence acquisition

We show that the valence acquired by an object is sensitive to the perceived attention it receives and that this effect occurs in a quite implicit fashion. Participants were exposed to products (i.e., peppermint brands) associated with the head of dogs oriented toward them, looking straight ahead, or oriented away from them. Participants then completed an affective priming task, which allowed us to assess the valence acquired by the products in a task free of desirability concerns. Results show that the valence of the products increased linearly as the perceived orientation of attention of the targets moved toward them. This finding suggests that mimetic desire effects may be activated in a quite implicit fashion. The theoretical and social implications of this finding are discussed.     

Effect of stationary objects on illusory forward self-motion induced by a looming display

It has previously been shown that when a moving and a stationary display are superimposed, illusory self-rotation (circular vection) is induced only when the moving display appears as the background. Three experiments are reported on the extent to which illusory forward self-motion (forward vection) induced by a looming display is inhibited by a superimposed stationary display as a function of the size and location of the stationary display and of the depth between the stationary and looming displays. Results showed that forward vection was controlled by the display that was perceived as the background, and background stationary displays suppressed forward vection by about the same amount whatever their size and eccentricity. Also, the perception of foreground-background properties of competing displays determined which controlled forward vection, and this control was not tied to specific depth cues. The inhibitory effect of a stationary background on forward vection was, however, weaker than that found with circular vection. This difference makes sense because, for forward body motion, the image of a distant scene is virtually stationary whereas, when the body rotates, it is not.     

Effects of varying force production in practice schedules of children learning a discrete motor task

The variability of practice prediction from Schmidt's Schema Theory involving transfer and retention was tested when manipulating only the performance parameter of over-all force. Children (n = 120) of two age groups performed a 15-in (39.1 cm) arm movement on a linear slide modified to allow manipulating the force required to move the car on the slide. No significant differences between the variable group and the constant practice group were found for either the 10 transfer or 5 retention trials. Mean absolute errors were ordered in favor of the constant practice group for both transfer and retention. For the first transfer trial a significant difference was found; constant practice groups performed better. This finding is contrary to predictions of schema theory as well as evidence from children as subjects.     

Event-related potentials elicited by automatic targets: a dual-task analysis

The role of limited capacity processes in the detection of automatic targets was investigated in a dual-task paradigm using both behavioral and event-related brain potential (ERP) measures. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic (POC) showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). In addition, the latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of two separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses.     

Induced movement-in-depth and induced changing-size elicited by a luminous rotating spiral

Induced movement-in-depth and induced changing-size are infrequently investigated forms of a phenomenon whereby movement is ascribed to a stationary stimulus. The present note concerns qualitative responses to a display designed to elicit both forms. The inducer was a two-arm luminous rotating linear-function spiral, and the stationary stimulus was an annulus concentric with the spiral; it was patterned with concentric luminous circles. Viewing was monocular. Among the findings, induced movement-in-depth was more frequently reported than induced changing-size, despite the lack of veridical movement-in-depth in the display. Possible lines of explanation are suggested.     

The perception of self-motion induced by central and peripheral visual stimuli moving in opposite directions

The effects of the size of a stimulus and its eccentricity (central or peripheral) on the visually induced perception of horizontal translational self-motion (vection) were investigated. The central and peripheral areas of the observers' visual field were simultaneously stimulated by random dot patterns that moved in opposite directions. The results of two experiments indicated that the effects of central and peripheral presentations of the moving visual pattern are equivalent, and that vection strength is determined by the stimulus size and speed but not by its eccentricity. These results are consistent with the findings of previous studies that suggested that there are no qualitative differences in the vection-inducing potentials of the central and peripheral areas of the visual field, and are counter to the more traditional hypothesis, which has assumed that the perception of self-motion is specifically assigned to peripheral vision.     

Synesthetic colors are elicited by sound quality in Japanese synesthetes

Determinants of synesthetic color choice for Japanese phonetic characters were studied in six Japanese synesthetes. The study used Hiragana and Katakana characters, which represent the same set of syllables although their visual forms are dissimilar. From a palette of 138 colors, synesthetes selected a color corresponding to each character. Results revealed that synesthetic color choices for Hiragana characters and those for their Katakana counterparts were remarkably consistent, indicating that color selection depended on character-related sounds and not visual form. This Hiragana–Katakana invariance cannot be regarded as the same phenomenon as letter case invariance, usually reported for English grapheme-color synesthesia, because Hiragana and Katakana characters have different identities whereas upper and lower case letters have the same identity. This involvement of phonology suggests that cross-activation between an inducer (i.e., letter/character) brain region and that of the concurrent (i.e., color) area in grapheme-color synesthesia is mediated by higher order cortical processing areas.     

Anticipatory reconfiguration elicited by fully and partially informative cues that validly predict a switch in task

Task-switching studies show no behavioral benefit of partially informative cues. However, ERP evidence of an early cue-locked positivity elicited by both fully and partially informative cues suggests that both cues trigger an anticipatory component of task set reconfiguration (Nicholson, Karayanidis, Davies, & Michie, 2006). We examined this apparent discrepancy using a cued-trials task-switching paradigm with three tasks. The ERP finding of an early cue-locked positivity was replicated for both switch-to cues, which validly predicted an upcoming switch trial and specified the new task set, and switch-away cues, which validly predicted an upcoming switch trial but not the new task set. This component was not elicited by a noninformative cue that did not specify whether the task would switch or repeat. Switch-away cues resulted in more accurate but not faster responding than did noninformative cues. Modeling of decision processes confirmed a speed-accuracy trade-off between these conditions and a preparation benefit for both switch-to and switch-away cues. These results indicate that both fully and partially informative cues elicit an early anticipatory component of task set reconfiguration that is reflected in the early cue-locked positivity. We argue that the pattern of results is most consistent with a task set inhibition account of this early anticipatory component of task set reconfiguration.     

Team Perceived Trustworthiness in a Complex Military Peacekeeping Simulation

Antecedents to trust (propensity to trust, perceived trustworthiness) and trust behaviors were examined in relation to team performance in a complex eight-mission military peacekeeping simulation. Teams were colocated or distributed and stayed in the same or transferred to a different context at task transfer. In Experiment 1, an ability and competence factor accounted for most of the variance in perceived trustworthiness and greater perceptions of teammates' abilities/competences predicted posttransfer performance. One's perception of how others perceived one's ability/competence increased over missions. In Experiment 2, propensity to trust did not predict performance; however, trust in others' and one's own ability/competence and trust behaviors predicted performance. At task and/or context transfer, teams produced more monitoring and less cooperating language in their communication.