A kinematic examination of dual-route processing for action imitation

The dual-route model of imitation suggests that meaningful and meaningless actions are processed through either an indirect or a direct route, respectively. Evidence indicates that the direct route is more cognitively demanding since it relies on mapping visuospatial properties of the observed action on to a performed one. These cognitive demands might negatively influence reaction time and accuracy for actions performed following a meaningless action under time constraints. However, how meaningful and meaningless action imitation processing is reflected in movement kinematics is not yet clear. We wanted to confirm whether meaningless action performance incurs a reaction time cost, whether the cost is reflected in kinematics, and, more generally, to examine kinematic markers of emblematic meaningful and meaningless action imitation. We examined participants’ reaction time and wrist movements when they imitated emblematic meaningful or matched meaningless gestures in either blocks of the same action type or mixed blocks. Meaningless actions were associated with a greater correction period at the end of the movement, possibly reflecting a strategy designed to ensure accurate completion for less familiar actions under time constraints. Furthermore, in mixed blocks, trials following meaningless actions had a significantly increased reaction time, supporting previous claims that route selection for action imitation may be stimulus-driven. However, there was only convincing evidence for this effect with an interval of ~2,948ms, but not ~3,573ms or ~2,553ms, between movements. Future work motion-tracking the entire hand to assess imitation accuracy, and more closely examining the influence of duration between movements, may help to explain these effects.     

How does orthographic knowledge influence performance on phonological awareness tasks?

Three experiments explored the nature of orthographic influences on performance on phonological awareness tasks. Experiment 1 demonstrated that adults find it easier to perform phoneme deletions on items where there is a direct correspondence between letters and target sounds (e.g., take the /r@/ from struggle) than where there is not (e.g., take the /w@/ from squabble). Analogous results were found in a phoneme reversal task. Spelling production ability tended to correlate more strongly with performance on the former type of item than on the latter, suggesting that elevated performance on phonological awareness tasks is associated with the use of orthographic information. Experiment 2 produced similar results in Grade 5 children. Experiment 3 suggested that adults cannot inhibit orthographic activation when it is disadvantageous to them, as they performed no better on items such as squabble when they were presented in pure blocks than when they were presented in mixed blocks. It is concluded that there are substantial automatic orthographic influences on phonological awareness task performance that need to be taken into account in interpreting data concerning the relationship between phonological awareness and reading.