Abstract
Overlearning (i.e. extending practice at asymptote) is known to enhance retention (Postman, 1962). Shibata et al., (2017) examined the effect of overlearning on subsequent learning and found it leading to an increased inhibitory state and anterograde interference (i.e. detrimental effect of prior learning on future learning; A-B). Recent work from our laboratory (Hamel et al., 2021) showed that, if constrained into a close temporal window, learning twice the same task (A-A) also leads to anterograde interference. These findings dispute the assumption that exposure to a perturbation necessarily leads to faster re-adaptation the second time (i.e. savings; Krakauer, 2009). The objective of this work was to test whether increasing the duration of practice would increase the degree of anterograde interference. In a fully within-subject and counterbalanced design, four conditions were carried out where participants (n = 24) adapted to 20° gradual visual deviation while the length or type of the performance asymptote was manipulated. The performance asymptote at 20° was either Short (40 trials), Moderate (160 trials), Long (320 trials), or kept changing around 20° for 160 trials (Jagged). Following a 2-minute break, participants were re-exposed to the same visual deviation and practiced at performance asymptote for 40 trials. Namely, increasing the duration of asymptote (Short to Moderate) increased anterograde interference. Surprisingly, no further increase was detected (Moderate to Long), suggesting the presence of a ceiling effect. One interpretation is that the increased inhibitory state is prompted by the accumulation of adenosine due to the energy-consuming metaplasticity of sensorimotor adaptation.
