Rapid Reaching Task

Background

The Rapid Reaching Task (RRT) is an experimental paradigm to study how the human brain plans, adjusts, and executes fast movements toward a visual target. Julia Trommershäuser and colleagues used it in 2003 to study the relationship between economic risk and reward to quick motor planning in everyday visuomotor situations when wrong choices could be costly. For example, soccer players have to rapidly decide where to shoot the ball into the goal (the target area) without being 'penalized' by the opposing team.

Trommershäuser et al designed a computerized RRT task that asked participants to rapidly move a response finger from a computer spacebar to a specific target area on the computer while at the same time avoiding a close (overlapping) penalty area. Participants did not get a lot of time for responding (btw. 400-700ms), thus they could not carefully aim and had to rely on their motor system's automatic responses. Trommershäuser et al found that the adult human motor planning system actually acted in accordance with an "ideal movement planner" who automatically assessed and aimed at an optimal spot in the target area to maximize financial gain and minimize risk.

This ability of our motor system, however, needs time to develop. In their 2016 study on the development of rapid movements under economic risk, Tessa Dekker and Marco Nardini showed that children under the age of 10 -and even at 11- consistently made risky, suboptimal reaches, often aiming too close to the penalty zone. They concluded that the integration of risk and motor probability has a protracted development and matures much later in adolescence.

The default implementation of the Millisecond Rapid Reaching Task checks if the current device has an external keyboard that is attached to a touchscreen. If so, 'pressing the [SPACE] key' is required to start each trial sequence (as the original Trommershäuser design). If no external keyboard or touchscreen is detected, a dedicated START button below the target frame is provided and the task can be run with the computer mouse. The task uses absolutely defined target sizes that can easily be adjusted if needed.

Task Procedure

The Millisecond RRT starts with a demonstration session to explain the general task. During the demonstration, participants learn to press the spacebar key of their keyboard (Note: the task can also be played with a dedicated 'Start' response button located on the screen) to initiate the next trial. Once participants press down on the spacebar, a blue framed area (= response area) appears on the screen. Shortly thereafter a green circle (the target shape) appears somewhere in the vicinity of this response area. A filled circle overlaps with the green response area. This disk represents the 'penalty' area that should be avoided. Once the target circle appears, participants must lift their finger of the spacebar and press down on the green circle as fast as possible. Early lift-offs result in a trial repeat. If only the target area is hit, the participant gains a point. During the demonstration, no time limits are enforced, nor are any responses on the penalty circle penalized.

Before participants move on to the test phase, they work on 15 training rounds, each running 20 trials. The training starts with a time limit of 1000ms and adjusts this limit if 90% of the responses were made within this response window. No more adjustments are made for the last two blocks which are run with the final test time limit. Hitting only the target area results in a gain of 1 point. During training, the penalty circle is presented in gray and hitting it does not result in any penalties. Two different overlap distances between target and penalty circle are tested in a mixed design. During the training and the test session, participants are penalized for slow responses. Slow responses always result in the deduction of 7 points as well as in a delay of the next trial by 20 seconds.

The test consists of two parts: one round of testing uses a small penalty amount for hitting the penalty circle and the other a high amount. Each round runs five consecutive blocks of 20 trials each. The order of the two conditions can be counterbalanced. During the 'Low Penalty Amount' round, the color of the penalty circle is blue, and participants lose 1 point when accidentally hitting it. During the 'High Penalty Amount' round, the color of the penalty circle is yellow and hitting it results in the deduction of 5 points. Hitting the 'target-only' area always results in winning one point. Again, two different overlap distances between target and penalty circles are tested within each penalty condition. Note that if participants hit the overlap region of target and penalty circle, both win and penalty amounts apply.

What it Measures

The Rapid Reaching Task (RRT) measures motor planning under economic risk

Psychological domains

• Decision-making: Response to potential rewards and losses over time
• Visuomotor Coordination: The ability of the brain, eyes, and body to work together on a task
• Psychomotor Speed: Ability of brain and muscles to work together fast to complete a physical movement task
• Visuospatial Coordination: Ability to perceive, analyze, and understand the physical space and the relationships between objects within it
• Cognitive Control: Ability to balance reckless speed and high-reward accuracy ('speed-accuracy' trade-off)

Main Performance Metrics

• Efficiency Scores: Response efficiency in each experimental condition is assessed considering the response coordinates and the individual's motor 'noise' (response variability) The most crucial condition is the one in which penalty circle is close to target and wrong movements yield a high penalty

Psychiatric Conditions

The Rapid Reaching Task (RRT) is intended for academic research. It is currently not used in clinical assessments.

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Rapid Reaching Task.

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Trommershäuser, J., Maloney, L. T., & Landy, M. S. (2003). Statistical decision theory and the selection of rapid, goal-directed movements. Journal of the Optical Society of America. A, Optics, Image Science, and Vision, 20(7), 1419. https://doi.org/10.1364/JOSAA.20.001419

Chapman, Craig S, Gallivan, Jason P, Wood, Daniel K, Milne, Jennifer L, Culham, Jody C, & Goodale, Melvyn A. (2010). Reaching for the unknown: Multiple target encoding and real-time decision-making in a rapid reach task. Cognition, 116(2), 168-176.

Chapman, Craig S, Gallivan, Jason P, Wong, Jeremy D, Wispinski, Nathan J, & Enns, James T. (2015). The Snooze of Lose: Rapid Reaching Reveals That Losses Are Processed More Slowly Than Gains. Journal of Experimental Psychology. General, 144(4), 844-863.

Dekker TM, Nardini M. Risky visuomotor choices during rapid reaching in childhood. Dev Sci. 2016;19(3):427–439