Flexible and inflexible response components: a Stroop study with typewritten output

Two experiments were directed at investigating the relationship between response selection and execution in typewriting, and specifically the extent to which concurrent processing takes place. In a Stroop paradigm adapted from [Logan, G. D., & Zbrodoff, N. J. (1998). Stroop-type interference: Congruity effects in colour naming with typewritten responses. Journal of Experimental Psychology: Human Perception and Performance, 24, 978–992], participants typed the names of colour patches with incongruent, congruent, or neutral distractors presented at various stimulus-onset asynchronies. Experiment 1 showed Stroop interference and facilitation for initial keystroke latencies and errors, contrasting with response durations (a measure of response execution) being unaffected by Stroop manipulation. Experiment 2 showed that all three measures were responsive to time pressure; again, Stroop effects were confined to latencies and errors only. The observation that response duration is both flexible under time pressure and protected from response competition, may imply either that response execution is structurally segregated from earlier processing stages, or that encapsulation develops during the acquisition of typing skills.     

Change detection evokes a Simon-like effect

The present experiment studied choice response context effects on the programming of response sequences using behavioural and electrophysiological methods. Participants were asked to produce responses differing in sequence length (1-key vs. 3-key responses) with either their left or right hand in a choice reaction time (RT) task. The choice response context was manipulated by a blocked or mixed execution of 1-key and 3-key responses. A sequence length effect on RT was observed in the blocked but not in the mixed condition. The time course of the lateralized readiness potential indicates a motoric locus of the sequence length effect, suggesting that the response hand is activated before the entire motor program is established.     

On the relations between action planning, object identification, and motor representations of observed actions and objects

Recent evidence suggests that viewing a static prime object (a hand grasp), can activate action representations that affect the subsequent identification of graspable target objects. The present study explored whether stronger effects on target object identification would occur when the prime object (a hand grasp) was made more action-rich and dynamic. Of additional interest was whether this type of action prime would affect the generation of motor activity normally elicited by the target object. Three experiments demonstrated that grasp observation improved the identification of grasp-congruent target objects relative to grasp-incongruent target objects. We argue from this data that identifying a graspable object includes the processing of its action-related attributes. In addition, grasp observation was shown to influence the motor activity elicited by the target object, demonstrating interplay between action-based and object-based motor coding.     

Learning by looking: Infants' social looking behavior across the transition from crawling to walking

This study investigated how infants gather information about their environment through looking and how that changes with increases in motor skills. In Experiment 1, 9.5- and 14-month-olds participated in a 10-min free play session with both a stranger and ambiguous toys present. There was a significant developmental progression from passive to active social engagement, as evidenced by younger infants watching others communicate more and older infants making more bids for social interaction. Experiment 2 examined longitudinally the impact of age and walking onset on this progression. The transition to independent walking marked significant changes in how often infants watched others communicate and made active bids for social interaction. Results suggest that infants transition from passive observers as crawlers to active participants in their social environment with the onset of walking.     

Adult modelling facilitates young children's generation of novel pretend acts

The present work investigated the effect of modelling on children's pretend play behaviour. Thirty‐seven children aged between 27 and 41 months were given 4 min of free play with a dollhouse and associated toy props (pre‐modelling phase). Using dolls, an experimenter then acted out a series of vignettes involving object substitutions, imaginary play and attribution of properties. Children were subsequently provided with an additional 4 min free play (post‐modelling phase). Consistent with past research, more pretence was exhibited after modelling than before. Furthermore, in the post‐modelling phase, children were as likely to generate their own novel pretence as they were to copy the actions demonstrated by the experimenter. They also increased the number of novel symbolic acts involving imaginary play from the pre‐ to the post‐modelling phase. This study highlights how young children will not only imitate a model's demonstration of pretend acts but also use this demonstration to catalyze the creation of their own pretence. Copyright © 2008 John Wiley & Sons, Ltd.     

观念运动理论：内涵与证据

人类日常动作有两种类型, 一是是对外界刺激的反应, 是一种自下而上的动作模式, 即感觉运动(sensorimotor)模式; 二是以人们头脑中的观念意图为基础, 由观念引导, 为了实现一个特定的目标而执行特定的动作, 是一种自上而下的动作模式, 即观念运动(ideomotor)模式。观念运动理论(ideomotor theory)所解释的就是以基于意图的动作。该理论经历了长期的演变, 一般动作执行与动作模仿领域内的行为与神经科学研究的证据初步证实了观念运动的理论构想与主要机制：共同编码机制与镜像神经机制。观念运动理论在贯通感知觉与动作方面具有重大意义, 由此还产生了共享环路模型(shared circuits model, SCM)等新近观点。此外, 观念运动理论还强调了目标和预期的重要地位。未来还需加强对动作与意图之间的通路, 以及动作的本体性效果等方面的研究。     

The social function of imitation in severe dementia

We report the case of Jessie, an individual with severe Alzheimer's disease. Over two sessions, we examine Jessie's spontaneous conversation behaviour and urge to communicate using the ‘still face’ paradigm. Spontaneous and deliberate imitation are also examined to identify their importance in social interactions in severe dementia. Although Jessie has difficulty producing meaningful conversation, she retains the urge to communicate and participate in social interactions. These results confirm the importance of imitation in facilitating and maintaining people with communication problems in the social world. Copyright © 2006 John Wiley & Sons, Ltd.     

Imitative interaction increases social interest and elicited imitation in non‐verbal children with autism

Recent studies indicate that being intensely imitated for a brief period of time increases social interest among children with autism. The aim of this study was to replicate and extend these findings. Twenty children with an autism spectrum disorder (ASD) were randomly assigned to one of two interaction strategies: imitation (n=10) or contingent (n=10). The children had little or no functional speech, and their developmental age averaged 25 months (mean chronological age =6:5 years). Both conditions were presented with repeated sessions of a modified version of Nadel's ‘still‐face’ paradigm (still‐face/intervention/still‐face/spontaneous play). The analysis revealed a significant increase of both proximal and distal social behaviours (touch and look at person) for the imitation condition, which confirms previous reports. In addition, an increase in elicited imitation, as measured with the PEP‐R developmental assessment procedure, was also observed for children in the imitation condition, but not in the contingent condition. This finding extends earlier reports in that it suggests that the social expectancies unlocked by imitation also spread to tasks outside the experimental setting. Copyright © 2006 John Wiley & Sons, Ltd.     

Influences of grasp selection in typically developing children

When reaching towards an object, adults favour grasps which, following the intended action, end in a comfortable position even when this requires them to start in an uncomfortable position (the end-state-comfort effect). However, this strategy is not consistently used by children who instead seem to favour a minimal pre-contact rotation of the hand, even when this results in an uncomfortable end position. In terms of multiple movements, the strategies used for grip selection are unclear; adults may still grasp for end-state-comfort given their propensity to plan to the end of a movement; however, children who are less able to concatenate movement may tend to start-state-comfort movements. The current study considered grip selection in children ranging from 4 to 12 years and in a group of adults. Participants were asked to rotate a disc so that an arrow pointed towards a specific target(s), the number of sequences in a movement was increased from one to three. Planning for end-state-comfort was seen in all participants and a clear developmental trajectory was identified whereby the relative comfort of an end position could be directly predicted by age in months. Adults and 10–12-year-olds favoured an end-state-comfort strategy whereas the younger children gave equal weighting to end-state-comfort, start-state-comfort and no initial rotation strategies. All groups were able to end a movement comfortably when it was composed of three steps; however, the proportion of movements relying on an end-state-comfort strategy decreased as sequence length increase whereas the proportion of start-state-comfort and no initial rotation strategies increased. The current data support the concept that a mechanism for planning grasps may be based on motor experience.