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Asymmetries In Motor Attention During A Cued Bimanual Reaching Task: Left And Right Handers Compared, Gavin Buckingham, Julie Main, David Carey

Gavin Buckingham

Several studies have indicated that right handers have attention biased toward their right hand during bimanual coordination (Buckingham and Carey, 2009; Peters, 1981). To determine if this behavioral asymmetry was linked to cerebral lateralization, we examined this bias in left and right handers by combining a discontinuous double-step reaching task with a Posner-style hand cueing paradigm. Left and right handed participants received a tactile cue (valid on 80% of trials) prior to a bimanual reach to target pairs. Right handers took longer to inhibit their right hand and made more right hand errors, suggesting that their dominant hand was more …

Bimanual Reaching Across The Hemispace: Which Hand Is Yoked To Which?, Gavin Buckingham, Gordon Binsted, David Carey

Gavin Buckingham

When both hands perform concurrent goal-directed reaches, they become yoked to one another. To investigate the direction of this coupling (i.e., which hand is yoked to which), the temporal dynamics of bimanual reaches were compared with equivalent-amplitude unimanual reaches. These reaches were to target pairs located on either the left or right sides of space; meaning that in the bimanual condition, one hand's contralateral (more difficult) reach accompanied by the other hand's ipsilateral (easier) reach. By comparing which hand's difficult reach was improved more by the presence of the other hand's easier ipsilateral reach, we were able to demonstrate asymmetries …

Rightward Biases During Bimanual Reaching, Gavin Buckingham, David Carey

Gavin Buckingham

Two experiments were carried out to investigate whether attention is biased toward the right hand of right handers during bimanual coordination (Peters 1981). A novel discontinuous double-step reaching task was developed, where right-handed participants executed a bimanual reach followed by a left or right hand unimanual reach. Asymmetries in the downtime between the bimanual and unimanual reach portions (the refractory period) were used to infer the direction of attention. A shorter right hand refractory period was found in the first experiment, indicating a rightward bias in attention. In a second experiment, shifting the focus of attention during the bimanual portion …

Investigating Bimanual Coordination In Dominant And Non-Dominant Virtual Hands, Gavin Buckingham, David Carey

Gavin Buckingham

A bias in attention towards the dominant hand has been cited as a possible factor in the lateralisation of human bimanual coordination (Peters, 1981). A mirror was placed between the hands of 18 dextral participants performing rhythmic anti-phase movements. This set-up gave the appearance of a reflected virtual hand (moving in time with the un-occluded hand), in the same spatial location as the occluded left or right hand. This asymmetrical conflict between vision and action examined whether the left hand would show higher levels of error when replaced by a virtual right hand than the converse condition. Higher levels of …

Bimanual Coupling In Left And Right Space: Which Hand Is Yoked To Which?, Gavin Buckingham, Gordon Binsted, David Carey

Gavin Buckingham

• Reaching across the body into contralateral space with one hand incurs a substantial cost on various measures of performance, compared to ipsilateral reaches of a similar amplitude (Carey, Hargreaves, & Goodale, 1996).

• When reaching with both hands, unimanual asymmetries disappear.

-The hands take off and land concurrently (Kelso, Southard, & Goodman, 1979).

• To test if this ‘yoking’ is driven by the left or the right hand, participants performed reaches of different amplitudes.

• These reaches were made to the left or right side of space.

-Further increasing the unimanual (baseline) asymmetries that get wiped out by the …

Asymmetries In Attention Toward The Dominant Hand: Input Or Output?, Gavin Buckingham, Julie Main, David Carey

Gavin Buckingham

Peters (1981) suggested that an asymmetrical bias in attention (toward the right hand of right handers) could account for many manual asymmetries in bimanual task performance. Support for this notion comes from Honda (1982), who demonstrated preferential monitoring of the dominant hand during a bimanual reaching task, while Buckingham and Carey (2007) observed shorter refractory periods (dwell time in a bimanual discontinuous double-step reaching task) for the right hand.

Recent evidence may indicate an intentional (i.e. selection related behaviour – motor attention) bias toward the dominant hand (Bestelmeyer & Carey, 2004). The current study tests the hypothesis that the right …