Developmental Coordination Disorder (DCD) is characterised by impairments to motor control and learning, the cause of which remains unclear. Recently, researchers have used cognitive neuroscientific approaches to explore the basis of poor coordination in children, with one hypothesis suggesting that an internal modelling deficit (IMD) is one of the underlying causes of DCD. The aim of this thesis was to further test the IMD hypothesis using a motor imagery paradigm - the mental rotation of hands. Versions of this task were used in all studies to assess motor imagery ability, with an additional whole-body task used in Studies 2 and 3. Further, an alphanumeric rotation task was used in Studies 1 and 2 to assess visual imagery ability. Studies 1 and 2 provided varying levels of support for the IMD hypothesis. In Study 1, only a subgroup of DCD children performed differently from other children in the study on the hand tasks, but tighter task constraints in Study 2 led to overall group differences between DCD and controls in terms of accuracy. The DCD group were also significantly less accurate than controls in the whole-body task, but there were no group differences in either Study 1 or 2 on the visual imagery task. Interestingly, in Study 2, there was an indication that children with severe levels of motor impairment were less accurate than children with less severe motor impairment, suggesting that motor impairment level could play a role in the severity of motor imagery deficits. Study 3 was designed to explore the impact of motor impairment severity on motor imagery ability further. The results confirmed that children with severe DCD had greater motor imagery impairment than children with mild DCD - children with severe DCD performed less accurately than both controls and those with mild DCD in the hand task with instructions and the controls in the whole-body task. Further, those children with mild DCD were able to respond somewhat to motor imagery instructions, whereas those with severe DCD were not. This study provided support to the IMD hypothesis, though the deficit was shown to be dependent on a number of factors. Chapter 5 presents a reasoned account of these various findings and their implications are discussed. It is concluded that motor imagery deficits are evident in many children with DCD, but more so in children with severe motor impairment. A general imagery deficit was ruled out based on the findings of Studies 1 and 2 which showed that visual imagery processes appear intact in children with DCD. Taken together with previous imagery and IMD studies, and related research on feedforward control in DCD, it is concluded that the deficits in motor imagery observed in this thesis are consistent with the hypothesis that an IMD is one likely causal factor in the disorder, particularly in more severe DCD. The observation of differing response patterns between children with mild and severe forms of DCD has important implications for developing a theory of DCD and for remediation.

Previous investigations comparing direct versus indirectly cued movements have consistently shown that indirectly cued movements take longer to prepare (Neely and Heath, 2010) and involve the recruitment of additional brain areas (Connolly et al., 2000). This increase in processing time has been associated with the additional cognitive transformations required of the task (Neely and Heath, 2010). In the present study we investigated whether differences between direct versus indirectly cued movements are also reflected in the time course of motor preparation. Participants performed a targeting task, moving directly to the location of a visual cue (i.e., directly cued movement) or to a location that differed by 60˚, 90˚, or 120˚ with respect to the visual cue provided (i.e., indirectly cued movements). Participants were instructed to initiate their movements concurrently with an anticipated go-signal. To examine the time course of motor preparation, a startling acoustic stimulus (SAS, 124dB) was randomly presented 150 ms, 500 ms, or 1000 ms prior to the go-signal. Results from the startle trials revealed that the time course of motor preparation was similar regardless of the angle of rotation required and hence whether it was a direct or indirectly cued trial. Specifically, motor preparation was delayed until less than 500 ms prior to movement initiation for both direct and indirectly cued movements. These findings indicate that similar motor preparation strategies are engaged for both types of cued movements, suggesting that the time to prepare a motor response may be similar regardless of whether a cognitive transformation is required.

To investigate the role of action representations in the identification of upright and rotated objects, we examined the time course of their evocation. Across five experiments, subjects made vertically or horizontally oriented reach and grasp actions primed by images of handled objects that were depicted in upright or rotated orientations, at various Stimulus Onset Asynchronies: -250 ms (action cue preceded the prime), 0 ms, and +250 ms. Congruency effects between action and object orientation were driven by the object's canonical (upright) orientation at the 0 ms SOA, but by its depicted orientation at the +250 ms SOA. Alignment effects between response hand and the object's handle appeared only at the +250 ms SOA, and were driven by the depicted orientation. Surprisingly, an attempt to replicate this finding with improved stimuli (Experiment 3) did not show significant congruency effects at the 0 ms SOA; a further examination of the 0 ms SOA in Experiments 4 and 5 also failed to reach significance. However, a meta-analysis of the latter three experiments showed evidence for the congruency effect, suggesting that the experiments might just have been underpowered. We conclude that subjects initially evoke a conceptually-driven motor representation of the object, and that only after some time can the depicted form become prominent enough to influence the elicited action representation. / Graduate / 0633 / ragavk@uvic.ca

Research has shown a possible causative link between playing the popular videogame Tetris and improvements in Mental Rotation performance. The aim of the present study was to address a question about an aspect of Tetris expertise that had not yet been factored into any of the existing work on Tetris and Mental Rotation. David Kirsh and Paul Maglio (1994) have shown that skilled Tetris players appear to use physical actions as substitutes for, or compliments to, mental operations. This is hypothesised to include physically rotating game pieces instead of Mentally Rotating them. The specific question we sought to address in the present study was whether these physical substitutes for mental operations, which Kirsh and Maglio call epistemic actions, have an effect on Tetris' efficacy as a Mental Rotation training task. In order to address this research question, three groups of subjects were administered tests of Mental Rotation ability before and after a five week training period. The training period consisted of a total of five, hour long, laboratory sessions - evenly spaced across the training period - in which each of the three groups were required to play an assigned video-game. The results showed that a group of subjects (N=13) who received Tetris training on the version of the game that made epistemic actions involving rotation impossible showed no greater Mental Rotation performance gains when their results were compared to a group of subjects (N=13) trained using a Standard version of Tetris. This suggests that the occurence of epistemic actions does not have an impact on Tetris' efficacy as a Mental Rotation training task. Further, neither of these two groups showed greater Mental Rotation performance gains than the non-Tetris control group (N=14), a result which suggests that, at least under some circumstances, Tetris training fails to impart Mental Rotation performance gains any greater than what can be expected due to retest effects. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 217-229.

Honors Project--Smith College, Northampton, Mass., 2009. / Includes bibliographical references (p. 40-42).

Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2010. / Committee Member: Alexander Gray; Committee Member: Charles Lee Isbell Jr.; Committee Member: Melody Moore Jackson; Committee Member: Paul M. Corballis; Committee Member: Thad Starner. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of California, San Diego, 2005. / Title from first page of PDF file (viewed March 7, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 135-142).

Previous investigations comparing direct versus indirectly cued movements have consistently shown that indirectly cued movements take longer to prepare (Neely and Heath, 2010) and involve the recruitment of additional brain areas (Connolly et al., 2000). This increase in processing time has been associated with the additional cognitive transformations required of the task (Neely and Heath, 2010). In the present study we investigated whether differences between direct versus indirectly cued movements are also reflected in the time course of motor preparation. Participants performed a targeting task, moving directly to the location of a visual cue (i.e., directly cued movement) or to a location that differed by 60˚, 90˚, or 120˚ with respect to the visual cue provided (i.e., indirectly cued movements). Participants were instructed to initiate their movements concurrently with an anticipated go-signal. To examine the time course of motor preparation, a startling acoustic stimulus (SAS, 124dB) was randomly presented 150 ms, 500 ms, or 1000 ms prior to the go-signal. Results from the startle trials revealed that the time course of motor preparation was similar regardless of the angle of rotation required and hence whether it was a direct or indirectly cued trial. Specifically, motor preparation was delayed until less than 500 ms prior to movement initiation for both direct and indirectly cued movements. These findings indicate that similar motor preparation strategies are engaged for both types of cued movements, suggesting that the time to prepare a motor response may be similar regardless of whether a cognitive transformation is required.

The primary focus of this study examines the effectiveness of the CRIOSAT (Computerized Rotational Isometric and Orthographic Spatial) spatial ability treatment on a random sample of middle school students’ (n=137) spatial ability as measured by the Purdue Spatial Visualization Test: Rotations Test (PSVT-ROT) (Guay, 1977). The secondary focus of this study investigates the relationships between mathematical achievement, problem solving preferences, and spatial ability. The secondary focus was tested on a subsample (n=41), with the problem solving preferences measured via the Mathematical Processing Instrument (MPI) (Suwarsono, 1982). Findings indicated no significant gains in spatial ability scores after students’ use of the CRIOSAT treatment; while some increases in spatial ability took place in males. Significant positive correlation was identified between mathematics achievement and spatial ability; while conversely, a significant negative correlation was found between mathematics achievement and level of visual problem solving used by students.