Biomedical subjects

Digby Elliott

Publications and source records attributed to Digby Elliott.

40 records · Page 3Linked to original sources

PubMed2003

Intermittent vision and one-handed catching: the temporal limits of binocular and monocular integration.

The aim of this research was to examine the temporal limits of binocular and monocular integration useful for one-handed catching. Participants performed 20 one-handed catching trials in 12 conditions (N = 240) defined according to the type of viewing (binocular, monocular) and the manipulation of the visual sample (continuous, intermittent). Catching performance deteriorated significantly when there was no visual information available for 80 ms between 20-ms visual samples provided simultaneously to each eye. However, there was no change in catching performance when continuous monocular vision was available for 80 ms between the binocular samples. Performance under monocular viewing decreased significantly when intermittent samples were separated by less than 20 ms. These results confirm that the equivocality in previously reported temporal limits of binocular integration is due to the different arrangement of the intermittent vision conditions and hence the information available between intermittent samples.

Adult↗

PubMed2002

A ménage à trois: the eye, the hand and on-line processing.

This review summarizes research conducted in our laboratories over the past 5 years aimed at determining the temporal and spatial relationships between eye and hand movements and the amount of central processing that must occur before performing a manual aiming movement, relative to the amount of processing that is done online. All of our research to date points to a two-component model of speed-accuracy control in manual aiming. Several studies have shown that eye and hand movements in manual aiming are inextricably linked both temporally and spatially. Typically, the eye arrives in the vicinity of the target first; this coincides with peak acceleration of the finger during the initial impulse phase of a movement. There is also significant temporal and spatial coupling of the finger, elbow and shoulder in aiming, and movements appear to evolve in a proximal-to-distal fashion. Movements are endpoint driven and variability is reduced with distal approximation to the target. This movement control strategy means that visual information is not only available for use in modifying responses, but there is sufficient time available for its use. In sequential complex aiming movements, the use of visual feedback and on-line processing become even more important. Practice does not diminish the need for on-line processing; rather, its use appears to ensure greater movement efficiency.

Biomechanical Phenomena↗

PubMed2002

Speech production errors in adults with and without Down syndrome following verbal, written, and pictorial cues.

Adults with Down syndrome and adults with developmental delays not related to Down syndrome were asked to read, repeat, and formulate speech from a picture following the presentation of 2- and 4-word and picture sequences. The speech sequences were produced either immediately after stimulus presentation or following a 5-sec response delay. Overall, participants with Down syndrome produced more memory errors than persons without Down syndrome. Participants with Down syndrome also committed more speech production errors than the other participants, but only when they were required to repeat what they had heard, or to formulate speech from pictures. The speech production performance of the two groups was equivalent in the read condition. These results are discussed with reference to Elliott, Weeks, and Elliott's (1987) model of cerebral specialization, and to verbal short-term memory in persons with Down syndrome.

Adult↗

PubMed1999

Goal-Directed Aiming: Correcting a Force-Specification Error With the Right and Left Hands.

In 2 experiments, the authors examined manual aiming asymmetries as well as the ability of participants to adjust their aiming trajectories following an unexpected change to the inertial resistance to movement. In Experiment 1, participants (N = 11) were able to rapidly adjust their movement trajectories to conform to the new movement requirements. They were faster and more consistent when aiming with their right hand than with their left hand, regardless of whether or not the movement was perturbed. In Experiment 2, participants' (N = 11) vision of the hand was manipulated so that the role of visual feedback in the corrective process could be examined. Vision had an impact not only on performance but also on the characteristics of the movement trajectories. Manual asymmetries in aiming were associated with a right hand superiority during the final corrective stages of the movement.

Journal Article↗