1. Bimanual reaches with symbolic cues exhibit errors in target selection
Jarrod Blinch, Brendan Cameron, Ian Franks, Romeo Chua
School of Human Kinetics
University of British Columbia
motorbehaviour.wordpress.com

2. Research question
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater coupling?

3. Kelso, Southard, & Goodman, 1983
Define bimanual reach
Two types of coupling: temporal, spatial
Asymmetric movement
Coupling during movement execution, what about coupling during movement preparation?
Kelso, Putnam, & Goodman, 1979
Kelso, Southard, & Goodman, 1983

4. L S L L Symbolic cues Spatial cues Asymmetric movement
Coupling during movement preparation
Response selection or response programming, both measured by reaction time
Symbolic cues
Reaction times were longer for asymmetric movements compared to symmetric movements
Reaction time cost for asymmetric movements
RP or RS, if RP then any movement, regardless of the type of cue
Spatial cues
Equivalent RTs for symmetric and asymmetric movements
So…
Diedrichsen, Hazeltine, Kennerley, & Ivry, 2001

5. Reaction time cost with symbolic cues
Coupling during movement preparation
Increased processing demands on response selection
Translate two different symbolic cues
Assign a movement to each arm
fMRI
Increased processing in the medial frontal cortex
Pre-Supplementary motor area and the rostral cingulate zone
More cognitive-motor visuomotor processing compared to symmetric movements or spatial cues
This increase in cognitive processing for symbolically-cued asymmetric movements creates coupling during movement preparation, but what about movement execution, specifically spatial coupling?
Diedrichsen, Grafton, Albert, Hazeltine, & Ivry, 2006

6. Research question
Do bimanual reaches with more cognitive visuomotor control processes compared to more automatic control exhibit greater spatial coupling?

7. L S Method 16 participants Spatial and symbolic cues Optotrak
Cues: counterbalanced over two days

8. Replicated RT cost with symbolic cues and not spatial cues

9. Half of the trials from one participant
Symmetric in blue, Asymmetric in red
14% of symbolic asymmetric movements had large trajectory modulations
Spatial coupling or an online correction?

10. Symbolic, long-short, no modulations Symbolic, short-long, modulations
Left arm (blue) to the long-distance target
Velocity at 100 ms to examine what was programmed (before online control)
Not coupling during movement execution, but rather online corrections to errors in target selection
Also supported by delta reaction time

11. Discussion
Increased cognitive processing for response selection with symbolically-cued asymmetric movements
Coupling was also related to response selection
Reaction time cost
Errors in target selection
Coupling is limited to the processes that require greater cognitive control
Perhaps bimanual coupling is limited to the processes that require greater cognitive control
Increased cognitive control for response selection leads to coupling during response selection
We predict that experiments with spatial coupling likely had increased cognitive control to monitor movement execution, for example…
In conclusion, bimanual coupling is limited to the processes that require greater cognitive control

12. Spatial coupling Franz, Zelaznik, Swinnen, & Walter, 2001
Swinnen, Lee, Verschueren,
Serrien, & Bogaerds, 1997

13. Bimanual reaches with symbolic cues exhibit errors in target selection
Jarrod Blinch, Brendan Cameron, Ian Franks, Romeo Chua
School of Human Kinetics
University of British Columbia
motorbehaviour.wordpress.com

14. Movement time

15. Spatial

16. Symbolic

17. Delta reaction time (ms)
Symbolic, no modulations
Symbolic, modulations
Long-Short
-10.2
-0.4
Short-Long
0.6
-9.4
Delta reaction time
Time difference for the left and right arms to begin their movements, negative is a left arm lead
No modulations: large left hand head start of 10 ms for LS movements (handedness)
With modulations: large left hand head start for SL movements

18. Online response selection