A second punch with a different arm actually leaves the brain faster than a single punch initiated from a standstill.
Motor reactions follow a strange rule where starting an entirely new movement is quicker than adjusting one that is already happening. Most people assume that the brain takes longer to process two different actions than one simple one. The data shows that a target change triggers an urgency signal that bypasses standard motor preparation. This fast-forwards the second movement to the point where it beats the speed of the original action. This means the human brain is optimized for rapid-fire pivots rather than steady, singular tasks.
Punching Fast and Slow: Faster-Reacting but Slower-Moving the Second Punch Around
SSRN · 6690539
The latency of motor responses to visual stimuli is usually much shorter when the trajectory of an ongoing movement must be amended, e.g., to account for a change in target position, than when a new movement must be initiated. Here, we show that when a new movement (i.e., with a different limb) must be initiated in response to a sudden target change, the latency of movement initiation is also substantially reduced. Participants had to punch at 3D virtual targets, whose position could change at t