title: Spatial assimilation effects in sequential movements: effects of parameter value switching and practice organization.
abstract: In Experiment 1, the author extended earlier work by investigating spatial assimilations in sequential aiming movements when participants were able to preplan only the 1st movement of a 2-movement sequence. Right-handed participants (N = 20) aged 18-22 years tried unimanual rapid lever reversals of 20 degrees and 60 degrees with an intermovement interval of 2.5 s. Following the 1st movement, participants made a same-distance movement, different-distance movement, or no movement in a randomly determined order. Participants overshot the short-distance target and undershot the long-distance target for both movements in the sequence, but the errors were greater when the 2nd movement differed from the 1st one. In Experiment 2, right-handed participants (N = 20) demonstrated greater assimilation effects after random practice than after blocked practice of both same-distances (20 degrees -20 degrees and 60 degrees -60 degrees ) and different-distances (20 degrees -60 degrees and 60 degrees -20 degrees ) sequences, although spatial errors were greater in different-distances conditions than in same-distances conditions. Overall, the experiments showed that parameter-value switching and practice organization are 2 major sources of spatial inaccuracy in sequential aiming movements.
authors.affiliation: Department of Integrative Physiology, University of Colorado, Boulder CO 80309-0354, USA. Sherwood@Colorado.edu
authors.forename: David E
authors.initials: DE
authors.lastname: Sherwood
mesh_terms: D000223:Adaptation, Psychological; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D033182:Intention; D008297:Male; D009068:Movement / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D046709:Pattern Recognition, Physiological / Q000502:physiology; D011214:Practice, Psychological; D011597:Psychomotor Performance / Q000502:physiology*; D012016:Reference Values; D012691:Serial Learning / Q000502:physiology*; D012718:Set, Psychology; D013037:Spatial Behavior / Q000502:physiology*; D013997:Time Factors