Adapt and overcome: Examining adaptation processes under prismatic displacement


Humans often encounter machine interfaces or sensory conditions that require an adaptation of our sensory-motor mechanisms to efficiently complete actions. The adaptation processes of calibration and alignment were examined under prismatic displacement during rapid aiming. Eight females aimed at a target (0.5cm2) presented at one of three distances (35cm, 40cm, or 45cm). Participants completed 24 normal-vision pre-exposure trials while wearing liquid crystal goggles followed by three blocks of 30 trials with 30-Dioptre (17degree) rightward Fresnel prisms on the goggles. Afterward, participants completed a 24 trial post-exposure block. A Certus recorded 3D position at 500Hz for 2s. Separate 5-Block by 3-Target ANOVAs examined the influence of prism exposure and target distance. Participants demonstrated prolonged reaction time in the second exposure compared to the pre-exposure block, F(4, 28)=5.841, p=0.002, n2=0.455, which indicated a shift in premovement parameterisation as a result of prismatic adaptation. This notion was supported by an initial increase in movement time from pre-exposure to the first exposure block that dissipated as exposure to the prism progressed, F(4, 28)=6.335, p=0.001, n2=0.475. The increase in movement time was a direct result of an increase in time-after peak velocity, F(4, 28)=10.330, p<0.0001, n2=0.596. Constant error in the secondary axis was significantly rightward under the first exposure compared to the pre-exposure block. The negative after-effect in post-exposure was significantly to the left of the endpoints during the exposure blocks, F(4, 28)=26.158, p<0.0001, n2=0.789. Results indicate the need to consider the dynamic nature of adaptation processes within modern models of sensory-motor control.