Alberto Cordova

Is there an advanced aging effect on the ability to mentally represent action

Motor programming theory suggests that an integral component in an effective outcome is an adequate action (mental) representation of the movements; a representation reflected in the ability to use motor imagery. Recent reports show a decline with advanced age (>64 years) using a variety of motor simulation tasks. Here, we examined the possible effects of advanced age on motor imagery ability in the context of estimation of reachability--that is, estimating whether an object is within reach or out of grasp. Thirty young adults (mean age: 20) and 23 older adults (mean age: 77) were instructed to estimate, using motor imagery, whether randomly presented targets in peripersonal (within actual reach) and extrapersonal (beyond reach) space were within or out of reach of their dominant limb while seated. Results indicated that the younger group was significantly more accurate than the older adults, p < 0.001. Whereas both groups made more errors in extrapersonal space, the values were significantly higher for the older group; that is, they overestimated to a greater extent. In summary, these findings add to the general notion that there is a decline in the ability to mentally represent action with advanced age.

Examining the Effects of Postural Constraints on Estimating Reach

The tendency to overestimate has consistently been reported in studies of reachability estimation. According to one of the more prominent explanations, the postural stability hypothesis, the perceived reaching limit depends on the individuals perceived postural constraints. To test that proposition, the authors compared estimates of reachability of 38 adults (a) in the seated posture (P1) and (b) in the more demanding posture of standing on one foot and leaning forward (P2). Although there was no difference between conditions for total error, results for the distribution and direction of error indicated that participants overestimated in the P1 condition and underestimated in the P2 condition. It therefore appears that perceived postural constraints could be a factor in judgments of reachability. When participants in the present study perceived greater postural demands, they may have elected to program a more conservative strategy that resulted in underestimation.

Estimation of Reach in Peripersonal and Extrapersonal Space: A Developmental View

This study explored the developmental nature of action processing via estimation of reach in peripersonal and extrapersonal space. Children 5 to 11 years of age and adults were tested for estimates of reach to targets presented randomly at seven midline locations. Target distances were scaled to the individual based on absolute maximum reach. While there was no difference between age groups for total error, a significant distinction emerged in reference to space. With children, significantly more error was exhibited in extrapersonal space; no difference was found with adults. The groups did not differ in peripersonal space; however, adults were substantially more accurate with extrapersonal targets. Furthermore, children displayed a greater tendency to overestimate. In essence, these data reveal a body-scaling problem in children in estimating reach in extrapersonal space. Future work should focus on possible developmental differences in use of visual information and state of confidence.

Association between imagined and actual functional reach (FR): A comparison of young and older adults

Recent studies indicate that the ability to mentally represent action using motor imagery declines with advanced age (>64 years). As the ability to represent action declines, the elderly may experience increasing difficulty with movement planning and execution. Here, we determined the association between estimation of reach via use of motor imagery and actual FR. Young adults (M=22 years) and older adults (M=66 years) estimated reach while standing with targets randomly presented in peripersonal (within actual reach) and extrapersonal (beyond reach) space. Imagined responses were compared to the individuals scaled maximum reach. FR, also while standing, was assessed using the standardized Functional Reach Test (FRT). Results for total score estimation accuracy showed that there was no difference for age; however, results for mean bias and distribution of error revealed that the older group underestimated while the younger group overestimated. In reference to FR, younger adults outperformed older adults (30 versus 14in.) and most prominent, only the younger group showed a significant relationship between estimation and FR. In addition to gaining insight to the effects of advanced age on the ability to mentally represent action and its association with movement execution, these results although preliminary, may have clinical implications based on the question of whether motor imagery training could improve movement estimations and how that might affect actual reach.

A question of intention in motor imagery

We examined the question-is the intention of completing a simulated motor action the same as the intention used in processing overt actions? Participants used motor imagery to estimate distance reachability in two conditions: Imagery-Only (IO) and Imagery-Execution (IE). With IO (red target) only a verbal estimate using imagery was given. With IE (green target) participants knew that they would actually reach after giving a verbal estimate and be judged on accuracy. After measuring actual maximum reach, used for the comparison, imagery targets were randomly presented across peripersonal- (within reach) and extrapersonal (beyond reach) space. Results indicated no difference in overall accuracy by condition, however, there was a significant distinction by space; participants were more accurate in peripersonal space. Although more research is needed, these findings support an increasing body of evidence suggesting that the neurocognitive processes (in this case, intention) driving motor imagery and overt actions are similar.

Do Children Perceive Postural Constraints When Estimating Reach or Action Planning

Estimation of whether an object is reachable from a specific body position constitutes an important aspect in effective motor planning. Researchers who estimate reachability by way of motor imagery with adults consistently report the tendency to overestimate, with some evidence of a postural effect (postural stability hypothesis). This idea suggests that perceived reaching limits depend on an individuals perceived postural constraints. Based on previous work with adults, the authors expected a significant postural effect with the Reach 2 condition, as evidenced by reduced overestimation. Furthermore, the authors hypothesized that the postural effect would be greater in younger children. They then tested these propositions among children aged 7, 9, and 11 years by asking them to estimate reach while seated (Reach 1) and in the more demanding posture of standing on 1 foot and leaning forward (Reach 2). Results indicated no age or condition difference, therefore providing no support for a postural effect. When the authors compared these data to a published report of adults, a developmental difference emerged. That is, adults recognize the perceived postural constraint of the standing position resulting in under- rather than overestimation, as displayed in the seated condition. Although preliminary, these observations suggest that estimates of reach (action planning) continue to be refined between late childhood and young adulthood.

Affordances in the Home Environment for Motor Development: A Cross-Cultural Study between American and Lebanese Children

Considerable efforts have been devoted to map the relations between the home environment and selected aspects of child’s development. A recent instrument was developed that aimed at assessing the affordances in the home environment, the AHEMD-SR. Although the AHEMD-SR gave insight into affordances in the home, it was focused on two specific populations from the United States and Portugal. Currently, there is limited research regarding the validity of this instrument when used in different cultures. The purpose of this study was to compare a sample of Middle Eastern children to the normative sample that was used to validate the AHEMD. Results showed a significance difference between the socioeconomic statuses between the groups. Concerning factor analysis, results showed that the Lebanese group had five factors loading as did the American/Portuguese sample but with variables loading differently. Interestingly, the Lebanese group showed higher scores for affordances inside the home such replica toys and games. Our findings show that the state of the environment may play a role in the affordances and development. Future work is needed to look at the specific loading and possible variables that may be included in the AHMED-SR to look at other cultures that may have other limitations.

Effects of Physical Practice and Imagery Practice on Bilateral Transfer in Learning a Sequential Tapping Task

Recent research on bilateral transfer suggests that imagery training can facilitate the transfer of motor skill from a trained limb to that of an untrained limb above and beyond that of physical practice. To further explore this effect, the present study examined the influence of practice duration and task difficulty on the extent to which imagery training and physical training influences bilateral transfer of a sequential key pressing task. In experiment 1, participants trained on the key pressing task using their non-dominant arm under one of three conditions (physical practice, imagery practice, and no practice). In a subsequent bilateral transfer test, participants performed the sequential task using their untrained dominant arm in either an original order or mirror-ordered sequence. In experiment 2, the same procedures were followed as in experiment 1 except that participants trained with their dominant arm and performed the bilateral transfer task with their non-dominant arm. Results indicated that with extended practice beyond what has been employed in previous studies, physical practice is more effective at facilitating bilateral transfer compared to training with imagery. Interestingly, significant bilateral transfer was only observed for transfer from the non-dominant to the dominant arm with no differences observed between performing the task in an original or mirror ordered sequence. Overall, these findings suggest that imagery training may benefit bilateral transfer primarily at the initial stages of learning, but with extended training, physical practice leads to larger influences on transfer.

Does General Motor Imagery Ability (via Questionnaire) Predict Estimation of Reachability in Children

With the present study we addressed the question of whether general motor imagery ability (MIA), as determined by questionnaire, predicts estimation of reachability in children ages 6 to 12 years of age. Estimation of reachability involves the use of motor (kinesthetic) imagery to derive a perceptual/cognitive (verbal) estimate of whether an object is within or out of reach. Our initial prediction was that older children would score higher than their younger counterparts in MIA, resulting in more accurate reach responses. Results indicated that, although younger childrens MIA scores were significantly lower than their older counterparts, reach responses were similar. Moreover, relationship analysis indicated a non-significant association between MIA and estimation of reachability. Explanations for the MIA difference focus on differences in cognitive ability and movement experience. Furthermore, we speculated that with the visual information provided by the reach task, the younger children were able to imagine reachability at a level comparable to their older counterparts. In essence, the results suggest that the MIA questionnaire and estimation of reach task tap different processing modes, which account for the differential outcome.

Bilateral transfer for learning to control timing but not for learning to control fine force

This study examined the characteristics of bilateral transfer of learning to control timing and fine force from a dominant limb to a nondominant limb. 20 right-handed college students (12 women, 8 men; M age = 21.5 yr., SD = 2.3) learned a sequential task consisting of timing and force control. Each participant completed a pre-test of the task with both hands and then performed 100 practice trials with the dominant hand. A post-test was conducted 1 hr. later. The results showed that after training, participants learned to control the timing and force. Nevertheless, only the time-control learning was transferred to the untrained hand, whereas the force-control learning did not transfer to the untrained hand.