Sensitivity of Smoothness Measures to Movement Duration,Amplitude, and Arrests

ABSTRACT

Studies of sensory-motor performance, including those concerned with changes because of age, disease, or therapeutic intervention, often use measures based on jerk, the time derivative of acceleration, to quantify smoothness and coordination. However, results have been mixed: some researchers report sensitive discrimination of subtle differences, whereas others fail to find significant differences even when they are obviously present. One reason for this is that different measures have been used with different scaling factors. These measures are sensitive to movement amplitude or duration to different degrees. The authors show that jerk-based measures with dimensions vary counterintuitively with movement smoothness, whereas a dimensionless jerk-based measure properly quantifies common deviations from smooth, coordinated movement.     

Learning Under Conditions of Action Information Feedback

Methodological and empirical issues in research on action information feedback (AIF) are discussed, with particular reference to the procedures and results of Annett (1970). Positioning responses practiced under conditions of AIF training are learned, though generally less well than under terminal IF conditions. Effects obtained as a result of AIF training may be subject to variations in movement extent required, gain and other transformations, frequency, temporal locus, and mode of augmentation, many aspects of which remain to be systematically studied.     

Immediate and Latent Interlimb Transfer of Gait Stability Adaptation Following Repeated Exposure to Slips

The authors trained 21 participants by using blocked-and-mixed exposure to right-side slips and then caused them to slip unexpectedly on the untrained left side. Authors retested participants with a right slip and a left slip at 1 week, 2 weeks, 1 month, and 4 months. The authors found that preslip stability on the first untrained left slip improved and was significantly greater than that on the first right slip, which probably contributed to the reduction in incidence of falls from ~30% to ~10%. Postslip stability and base of support (BOS) slip velocity were similar to those on the first right slip and much lower than those on the last right slip. Increases in pre- and postslip stabilities and BOS slip velocity during the left slip led to reductions in backward balance loss (BLOB) from ~95% on initial left slip to ~60% and to ~25% on the 1st and 3rd retest sessions, respectively. In contrast, BLOB remained at a constant ~40% level on the right slip of the same retest sessions. The results indicate a partial immediate transfer and a possible latent transfer.     

Feedback in Response Recognition and Production

The role of feedback in the development of recognition memory was examined by testing pairs of subjects; one subject performed the movement while the other listened to the movement in an adjacent room. Both groups of subjects developed recognition memory during training with KR, and recognition performance was virtually identical for both groups. In addition, previous experience with the sensory consequences of the movement led to improved response production during initial trials. A possible mechanism to account for this finding is proposed. Appreciation is extended to Richard A. Schmidt and Anne Marie Bird for helpful comments in earlier drafts of this paper.     

Bimanual and Unimanual Convergent Goal-Directed Movement Times

Three experiments are reported, investigating the effects of using 1 or 2 hands when making convergent low index of difficulty (ID) and visually controlled movements (2 hands meeting together). The experiments involved movements in four different cases—a probe held in the right hand and moved to a target held in the stationary left hand, vice versa of this arrangement, both hands moving with the probe in the right hand and target in the left hand, and vice-versa of this arrangement. Experiments were the standard Fitts’ paradigm, moving a pin into a hole and a low-ID task. In Fitts’ task, 2-hand movements were faster than 1 hand only at higher IDs; this was also the case in the pin-to-hole transfer task and the movement times were lower when the pin was held in the preferred hand. Movements made with low ID showed a small effect of 1- or 2-handed movements, with the effective amplitude of the movement being reduced by about 20% when 2 hands were used.     

Motor Programming Is Not the Only Process Which Can Influence RT

The current status of research on the memory drum theory is evaluated with emphasis on the issues raised by Marteniuk and MacKenzie (1981). A general theme emerging from this review is that response programming is not the only process which can influence RT and that distinguishing programming from non-programming effects clarifies rather than “clouds? the issues.     

Perceptual Estimates of Motor Skill Proficiency Are Constrained by the Stability of Coordination Patterns

This study demonstrated that motor skill proficiency ratings are constrained by the same order parameter dynamics that constrain action production and action perception processes. Participants produced rhythmic actions simulated by an animated stick figure of the human arm. The primary finding was that participants’ proficiency ratings covaried most with relative phase (φ) variability compared to mean relative phase. In-phase (φ = 0°) was produced with the least variability and received the highest proficiency rating, whereas the patterns φ = ±150° were attempted with the most variability and received the lowest proficiency ratings. A temporal delay in attempting to produce the animated pattern had a large impact on produced relative phase, yet had little impact on the proficiency ratings. Proprioceptive processes provide individuals information on motor skill proficiency. The lead or lag motion of the hand to forearm segment of the animated arm was identified consistently through visual processes and revealed asymmetries in the mapping of visual input to motor output. The results are consistent with concepts from the dynamic pattern theory of coordination and are discussed with regard to relative phase as an informational variable that constraints the perception-action system across many levels.     

Memory for Words as a Function of Spelling Transparency

The authors investigated the impact of spelling transparency on memory for words written in Persian orthography. Adult Persian university students (N = 212) performed in a memory recall experiment on 160 monosyllabic words printed on 8 cards (20 on each card) manipulated for spelling transparency, frequency, and imageability. Each card was presented randomly to the participants and they were asked to read the words aloud as quickly as possible. After reading each card, the participants were asked to engage in a digital addition task for 20 s (as a distracter), which was immediately followed by a request to write down as many words as possible from the cards in 40 s. No significant difference was found in the time to name aloud the opaque and transparent words, whereas on the memory recall task there were main effects for spelling, frequency, and imageability and significant 2-way and 3-way interactions. The effects were greatest for transparent spellings when they were of high frequency and high imageability or low frequency and low imageability. The implications of these findings are discussed.     

A Comparison of Single and Multi-Test Working Memory Assessments in Predicting Academic Achievement in Children

Children assessed as having low working memory capacity have also been shown to perform more poorly than their same-aged peers in measures of academic achievement. Early detection of working memory problems is, therefore, an important first step in reducing the impact of a working memory deficit on the development of academic skills. In this study, we compared a single-test assessment, the Working Memory Power Test for Children (WMPT) and a multi-test assessment, the Automated Working Memory Assessment (AWMA), in their ability to predict academic achievement in reading, numeracy, and spelling. A total of 132 Australian school children (mean age 9 years, 9 months) participated in the research. Strong positive correlations between the WMPT and AWMA total scores were found, indicating good convergent validity of the single and multi-test measures. WMPT scores correlated with each of the four AWMA subtests designed to assess verbal and visuospatial short-term and working memory. WMPT and AWMA scores separately predicted performance on Word Reading, Numerical Operations, and Spelling. Compared with either measure alone, the WMPT and the AWMA in combination predicted more of the variance in Word Reading and Numerical Operations, but not in Spelling. Theoretical and practical implications of these findings are discussed.     

Aurelius Augustine on Imagination

The evaluation of a person seeking or volunteering information in cooperatively or competitively oriented problem solving groups was investigated in 63 white and black, male and female, high school and college students. It was hypothesized that under cooperative conditions the seeking of information would be evaluated more positively than would the volunteering of information, while under competitive conditions the volunteering of information would be evaluated more positively than would the seeking of information. A highly trained confederate (C) engaged in either the seeking of information or the volunteering of information in four-person problem solving groups in which Ss were either cooperatively or competitively oriented. Ss rated Cs on eight bipolar scales. The results confirmed the hypothesis.