Eye-hand coordination in goal-directed aiming.

In a number of studies, we have demonstrated that the spatial-temporal coupling of eye and hand movements is optimal for the pickup of visual information about the position of the hand and the target late in the hand's trajectory. Several experiments designed to examine temporal coupling have shown that the eyes arrive at the target area concurrently with the hand achieving peak acceleration. Between the time the hand reached peak velocity and the end of the movement, increased variability in the position of the shoulder and the elbow was accompanied by a decreased spatial variability in the hand. Presumably, this reduction in variability was due to the use of retinal and extra-retinal information about the relative positions of the eye, hand and target. However, the hand does not appear to be a slave to the eye. For example, we have been able to decouple eye movements and hand movements using Müller-Lyer configurations as targets. Predictable bias, found in primary and corrective saccadic eye movements, was not found for hand movements, if on-line visual information about the target was available during aiming. That is, the hand remained accurate even when the eye had a tendency to undershoot or overshoot the target position. However, biases of the hand were evident, at least in the initial portion of an aiming movement, when vision of the target was removed and vision of the hand remained. These findings accent the versatility of human motor control and have implications for current models of visual processing and limb control.     

Attention shifts and the Simon effect: a failure to replicate Stoffer (1991)

The Simon effect refers to the intrusion of an irrelevant spatial dimension in the selection of a response to a stimulus. Recently, Stoffer (1991) proposed a specific role for attention orienting in the Simon effect. According to Stoffer, attentional shifts from an initial fixation point to a stimulus location are associated with the generation of a spatial code which specifies the position of the stimulus in relation to the last attended location. This spatial code forms the basis for the Simon effect because it is used to specify the selection of the right or left response. Three experiments were performed to examine further the attention-shift hypothesis forwarded by Stoffer. Experiment 1 was an attempt to replicate Stoffer (1991), but failed to do so. Experiments 2 and 3 were designed to optimize conditions for replicating crucial aspects of Stoffer's findings, but also failed to yield support for the attention-shift account.     

Response Selection Contributes to the Preparation Cost for Bimanual Asymmetric Movements

Movement preparation of bimanual asymmetric movements takes more time than bimanual symmetric movements in choice reaction-time conditions. This bimanual asymmetric cost may be caused by increased processing demands on any stage of movement preparation. The authors tested the contributions of each stage of movement preparation to the asymmetric cost by using the additive factors method. This involved altering the stimulus contrast, response compatibility, and response complexity. These manipulations changed the processing demands on stimulus identification, response selection, and response programming, respectively. Any manipulation with a larger reaction time cost than control suggests that stage contributes to the bimanual asymmetric cost. The bimanual asymmetric cost was larger for incompatible stimuli, which supports that response selection contributes to the bimanual asymmetric cost.     

Embodiment of motor skills when observing expert and novice athletes

If people are shown a dynamic movie of an action such as kicking a soccer ball or hitting a tennis ball, they will respond to it faster if it requires the same effector. This standard congruency effect was reported to reverse when participants viewed static images of famous athletes not actually performing an action. It was suggested that the congruent response was inhibited because of a social contrast effect, based on an implied action, whereby responders viewed themselves as comparatively worse than the professional athlete. The present study recorded hand and foot responses when identifying static images of both famous and novice athletes in soccer and tennis. The action was either explicit or implied. In Experiment 1, a standard congruency effect was found for all images. In Experiment 2, when a response was based on the identity of the athlete rather than their expertise, the standard congruency effect was enhanced for images of novice athletes, but was eliminated for experts, suggesting a social contrast effect. Our study is the first to show that embodiment effects can be seen for implied and explicit action images of both novices and experts, and that static images are capable of eliciting priming effects associated with sport-relevant effector pairings.     

Touch noise increases vibrotactile sensitivity in old and young

Stochastic resonance (SR) occurs when the detection of a subthreshold signal is aided by the presence of random energy fluctuations in the signal modality, commonly called noise. SR is counterintuitive because such noise usually worsens performance. Nonetheless, SR has been demonstrated both theoretically and experimentally in human sensory systems. Using a psychophysically sophisticated paradigm, we show that SR aids the detection of vibrating touch stimuli presented to the foot soles of both healthy elderly people with elevated vibrotactile thresholds and healthy young people with normal vibrotactile thresholds. The results also suggest that it is possible to know a priori the amount of noise needed for optimal SR effects given the degree to which the signal is subthreshold. Thus, SR may be practical as a rehabilitative aid for individuals with elevated sensory thresholds.     

Culture and diverging views of social events

The authors compared East Asians' and Americans' views of everyday social events. Research suggests that Americans tend to focus more on the self and to have a greater sense of personal agency than East Asians. The authors assessed whether, compared to East Asians, Americans emphasize main characters even when events do not involve the self and whether they see more agency or intentionality in actions, even when the actions are not their own. Whether East Asians would observe more emotions in everyday scenarios than would Americans also was investigated. In Study 1, Chinese and Americans read alleged diary entries of another person. Americans did focus more on main characters and on characters' intentionality. Study 2 replicated these results comparing Taiwanese and Americans on free recall of events concerning the self and of narratives and videos concerning others. Study 2 also found that Taiwanese made more comments about the emotional states of characters.     

Implicit scene learning is viewpoint dependent

When novel scenes are encoded, the representations of scene layout are generally viewpoint specific. Past studies of scene recognition have typically required subjects to explicitly study and encode novel scenes, but in everyday visual experience, it is possible that much scene learning occurs incidentally. Here, we examine whether implicitly encoded scene layouts are also viewpoint dependent. We used the contextual cuing paradigm, in which search for a target is facilitated by implicitly learned associations between target locations and novel spatial contexts (Chun & Jiang, 1998). This task was extended to naturalistic search arrays with apparent depth. To test viewpoint dependence, the viewpoint of the scenes was varied from training to testing. Contextual cuing and, hence, scene context learning decreased as the angular rotation from training viewpoint increased. This finding suggests that implicitly acquired representations of scene layout are viewpoint dependent.     

Smartphone use and daily cognitive failures: A critical examination using a daily diary approach with objective smartphone measures

While smartphones have brought many benefits and conveniences to users, there is continuing debate regarding their potential negative consequences on everyday cognition such as daily cognitive failures. A few cross-sectional studies have found positive associations between smartphone use and cognitive failures. However, several research gaps remain, such as the use of cross-sectional designs, confounds related to stable individual differences, the lack of validity in self-report measures of smartphone use, memory biases in retrospective self-reports, and the lack of differentiation between smartphone checking and smartphone screen time. To simultaneously address the aforementioned shortcomings, the current study examined the within-person associations between various objective indicators of smartphone use and daily cognitive failures using a 7-day daily diary study. Multilevel modelling revealed that smartphone checking, but not total smartphone screen time, predicted a greater occurrence of daily cognitive failures at the within-person level. Surprisingly, we also found negative within-person associations between smartphone screen time for social- and tools-related applications and daily cognitive failures, suggesting that some types of smartphone use may temporarily benefit one's cognitive functioning. This finding demonstrates the importance of studying the specific functions of smartphone use and their differential cognitive consequences, as well as highlights the complex relations between smartphone use and cognition.     

Decay in visuomotor representations during manual aiming

The time course of the decay of spatial representations used for planning and controlling manual aiming has not been established. The authors' purpose in the present investigation was to generate a psychometric function for memory-guided reaching movements. Eight university-aged students performed a reciprocal tapping task for 10 s. Participants could see the targets for 5 s; then, vision of the targets was occluded. The present findings provide mixed support for 2 prominent theories concerning memory representations. Variability increased concurrently with the removal of vision of the targets, supporting the real-time hypothesis. However, a brief plateau in the curve was apparent for approximately 2 s after vision was removed, consistent with the use of a highly accurate representation for action.