COORDINATION DYNAMICS AND ATTENTIONAL COSTS OF CONTINUOUS AND DISCONTINUOUS

BIMANUAL CIRCLE DRAWING MOVEMENTS

Jeff Summers, Sabrina Maeder, Cynthia Hiraga

University of Tasmania, Hobart, Australia

Tasmania

BACKGROUNDBACKGROUND•Different timing mechanisms have been proposed for

continuous and discontinuous movements (Semjen, 2002; Zelaznik et al. 2002, Ivry et al. 2004)

• Tasks that involve discontinuities (e.g., tapping) use a clock-like mechanism – – event timing

Explicit temporal goals set for successive discrete events with an internal timing system controlling movement onsets.

• Cerebellum important for event timing.

Temporal coupling between the hands arises through a common subcortical gating mechanism.

BACKGROUNDBACKGROUND

• Spatial and temporal coupling through communication across corpus callosum.

• In tasks involving continuous movements (e.g., circle drawing) timing may be an emergent process without continuous control from an internal timing system – Emergent timing

Temporal consistency may reflect processes associated with trajectory formation and control.

Zelaznik et al. (2002)Zelaznik et al. (2002)

1. Tapping

2. Unimanual Continuous Circle Drawing

3. Unimanual Intermittent Circle DrawingHigher correlations of temporal Higher correlations of temporal variability between tapping and variability between tapping and intermittent circle drawing (r = intermittent circle drawing (r = 0.5) than between continuous 0.5) than between continuous and intermittent circling tasks and intermittent circling tasks (r = 0.27)(r = 0.27)

800-ms MT

400-ms Movement

400-ms Pause

800-ms ITI

AIMSAIMS

1.To examine the coordination dynamics of discrete and continuous movements by comparing bimanual

continuous (CC) and intermittent (IC) circle drawing

Both continuous and intermittent circling tasks involve multijoint movements and task goal requires the production of coordinated bimanual periodic movements that conform to a specific trajectory. Intermittent circle drawing requires the insertion of a pause between each drawing cycle

AIMSAIMS

Event timing in intermittent circling:

a. Restricted to Pause Phase:

Pause – event timing + Movement – emergent timing

b. Hierarchical timer organisation:

Highest Level – time between movement onsets

Subordinate timer – pause interval

AIMSAIMS

•To compare the attentional demands of discrete and continuous bimanual movements

• To examine the relationship between coordination pattern stability and attentional demands in discrete and continuous movements

Central cost and pattern stability covary – (Temprado et al. 1999, 2001, Zanone et al. 2001)

TASKSTASKS

1. Continuous bimanual circle drawing

2. Intermittent bimanual circle drawing

Symmetrical Asymmetrical

Symmetrical Asymmetrical

Movement Time

Slow: 1000 ms (1 Hz)

Fast: 588 ms (1.7 Hz)

Pause: 400 ms (IC)

DUAL TASK PARADIGM

Bimanual Circle Drawing + Probe RT

Vocal RT

Task

METHODSMETHODS• Participants: 15 individuals right handers• Coordination Tasks:

Continuous (CC) - Intermittent (IC) Circle Drawing

Trial = 30-s continuation • Probe RT Task

6-8 tones (1400 Hz) per trial, ISI 500-1500 ms

RT task response – vocal• Conditions

Single-task: CC, IC, Probe RT

Dual-task: CC + probe RT, IC + probe RT

Prioritise coordination

DESIGNDESIGN

•2 X 2 X 2 X 2 Repeated Measures

•Task – Continuous, Intermittent Circle Drawing

•Attention – Single-task, dual-task

• Coordination mode – Symmetrical, Asymmetrical

(In-phase) (Anti-phase)

• Frequency – Slow (I Hz), Fast (1.7 Hz)

Sample Circle Drawing TrajectoriesSample Circle Drawing Trajectories

Continuous Circle Drawing

LH

RH

Intermittent Circle Drawing

LH

RH

LH RH

LH

RH

Temporal ValuesTemporal Values

______________________________________________ Task MT (ms) SE CV(%)

Slow Fast Slow Fast Slow Fast_______________________________________________________

Cont Circling 989 592 10.98 5.87 4.30 3.84

Inter Circling

Total 1410 998 16.54 9.95 4.54 3.86

Movement 965 689 12.58 7.89 5.05 4.43

Pause 445 309* 13.92 9.31 12.12 11.67 _______________________________________________________*Continuous – Slow = 1000 ms, Fast = 588 ms Intermittent – Slow = 1400 ms, Fast = 988 ms

Intermittent Circling - AttentionIntermittent Circling - Attention

Total Mov ement Paus e

P ortion

0

2

4

6

8

10

12

14

16

18

CV

Frequency (%

)

Single- tas k Dual- tas k

CorrelationsCorrelations

_________________________________ Intermittent Circling___________________________

Measure Total Movement Pause____________________________________________________

Continuous Circling - .02 - .10 .22

Intermittent Circling

Total .81 .64

Movement .56

Pause_____________________________________________________

Coordination Dynamics MeasuresCoordination Dynamics Measures

Control parameter: e.g., frequency

Order parameters: Collective level Component level

(between hands) (within hands)

Phase lag

(Relative tangential angle, RTA)

Variability/Stability

(Uniformity: 0-1)

Temporal(Circling Frequency, CV Freq)

Spatial(Aspect Ratio: 0-1, Spatial Error)

Coordination DynamicsCoordination Dynamics

1. Temporal Measures – AE RTA (Accuracy)

Continuous

Slow Fas t-5

0

5

10

15

20

25

30

35

40

45

50

55

60

AE

of RT

A (degree)

In termittent

Slow Fas t

In-phas e A nti-phas e

Task x Frequency x Coordination Mode

Coordination DynamicsCoordination Dynamics

1. Temporal Measures – Uniformity (Stability)

Task x Frequency x Coordination Mode

Continuous

Slow Fas t0.89

0.90

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1.00

1.01

Uniform

ity of RT

A

In termittent

Slow Fas t

In-phas e A nti-phas e

Coordination DynamicsCoordination Dynamics

2. Spatial Measures – Aspect Ratio (Circularity)

Slow

Continuous Intermittent0.74

0.76

0.78

0.80

0.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

Aspect R

atio

Fas t

Continuous Intermittent

Lef t-hand Right-hand

Task x Frequency x Hand

Coordination DynamicsCoordination Dynamics

2. Spatial Measures – Spatial Error (Variability)

Slow Fas t

Frequenc y

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Spatial E

rror (mm

)

Continuous Intermittent

Task x Frequency

REACTION TIMEREACTION TIME

240

260

280

300

320

340

360

380

Baseline Cont-In Cont-Anti Inter-In Inter-Anti

Med

ian

RT

(ms)

Slow

Fast

Stability and Probe RTStability and Probe RT

Uniformity Probe reaction time

Slow Fast

Frequency

290

295

300

305

310

315

320

Media

n R

T (

ms)

Continuous Intermittent

Slow Fast

Frequency

0.965

0.970

0.975

0.980

0.985

0.990

0.995

Mean U

nifo

rmity

of R

TA

Continuous Intermittent

REACTION TIMEREACTION TIME

Mean SE %age

Pause

Movement

373

373

17.53

15.13

36% (55)

64% (99)

• Different control processes involved in bimanual continuous and discontinuous movements

• Discontinuous movements involve a hierarchical temporal representation with the time between successive movement onsets represented at the highest level

• Continuous movements involve some form of emergent timing process

• Discontinuous movements incur greater central cost than continuous movements

ConclusionsConclusions

ConclusionsConclusions

• Continuous and discontinuous bimanual circling movements exhibit different coordination dynamics at high movement rates

• Both tasks showed a dissociation between stability and probe RT

SW Wilderness