Biomedical subjects

Kevin Shockley

Publications and source records attributed to Kevin Shockley.

5 recordsLinked to original sources

PubMed2006

Postural responses to specific types of working memory tasks.

Standing participants performed working memory tasks that varied along three dimensions: (1) type of information presented (verbal or visual); (2) the primary cognitive process engaged (encoding or rehearsal); and (3) interference that targeted the working memory components (phonological loop and visual sketchpad) believed primarily active during rehearsal. Postural sway variability decreased during rehearsal and increased during encoding. The effects during encoding, but not during rehearsal, differed for verbal versus visual material. Changes in cognitive activity were also associated with changes in the temporal patterns of postural sway. The results suggest postural control is sensitive to the type of cognitive task performed.

Adolescent↗

PubMed2005

Encoding and retrieval during bimanual rhythmic coordination.

In 2 experiments, bimanual 1:1 rhythmic coordination was performed concurrently with encoding or retrieval of word lists. Effects of divided attention (DA) on coordination were indexed by changes in mean relative phase and recurrence measures of shared activity between the 2 limbs. Effects of DA on memory were indexed by deficits in recall relative to baseline. For DA at both encoding and retrieval, the equilibrium values of relative phase were shifted and the degree of shared activity between left and right rhythmic motions was reduced. Recall was reduced, however, only for DA at encoding. The results corroborate and extend those obtained with more conventional secondary tasks (e.g., visual reaction time), suggesting attention dissimilarities between episodic encoding and retrieval.

Attention↗

PubMed2004

Imitation in shadowing words.

Imitation of shadowed words was evaluated using Goldinger's (1998) AXB paradigm. The first experiment was a replication of Goldinger's experiments with different tokens. Experiment 1's AXB tests showed that shadowed words were judged to be better imitations of target words than were baseline (read) counterparts more often than chance (.50). Order of presentation of baseline and shadowed words in the AXB test also significantly influenced judgments. Degree of prior exposure to token words did not significantly influence judgments of imitation. Experiment 2 employed modified target tokens with extended voice onset times (VOTs). In addition to AXB tests, VOTs of response tokens were compared across baseline and shadowing conditions. The AXB tests revealed shadowed words to be better imitations of target tokens than baseline, without an influence of AXB presentation order. Differences between baseline and shadowing VOTs were greater when VOTs were extended. The implications of spontaneous imitation in nonsocial settings are considered.

Adult↗

PubMed2004

Metamers in the haptic perception of heaviness and moveableness.

It is hypothesized that heaviness perception for a freely wielded nonvisible object can be mapped to a point in a three-dimensional heaviness space. The three dimensions are mass, the volume of the inertia ellipsoid, and the symmetry of the inertia ellipsoid. Within this space, particular combinations yield heaviness metamers (objects of different mass that feel equally heavy), whereas other combinations yield analogues to the size-weight illusion (objects of the same mass that feel unequally heavy). Evidence for the two types of combinations was provided by experiments in which participants wielded occluded hand-held objects and estimated the heaviness of the objects relative to a standard. Further experiments with similar procedures showed that metamers of heaviness were metamers of moveableness but not metamers of length. A promising conjecture is that the haptic perceptual system maps the combination of an object's inertia for translation and inertia for rotation to a perception of the object's maneuverability.

Humans↗

PubMed2003

Mutual interpersonal postural constraints are involved in cooperative conversation.

The research was designed to evaluate interpersonal coordination during conversation with a new measurement tool. The experiment uses an analysis based on recurrence strategies, known as cross recurrence quantification, to evaluate the shared activity between 2 postural time series in reconstructed phase space. Pairs of participants were found to share more locations in phase space (greater recurrence) in conditions where they were conversing with one another to solve a puzzle task than in conditions in which they convened with others. The trajectories of pairs of participants also showed less divergence when they conversed with each other than when they conversed with others well. This is offered as objective evidence of interpersonal coordination of postural sway in the context of a cooperative verbal task.

Adult↗