A progression of approximations to internal models of complex visuo-motor transformations Herbert Heuer ⇑ , Sandra Sülzenbrück IfADo – Leibniz Research Centre for Working Environment and Human Factors, Germany article info Article history: Available online 23 May 2012 PsycINFO classification: 2330 2343 Keyword: Adaptation abstract Previous research suggests that the acquisition of an internal model of a complex visuo-motor transformation might proceed as a pro- gression of approximations. Here, we test this assumption by com- paring performance of three groups of participants during practice and subsequent open-loop tests with three different types of visuo- motor transformation: the kinematic transformation of a sliding first-order lever, a point-symmetric transformation, and a line- symmetric transformation. With the point-symmetric transforma- tion, participants showed the most accurate performance from early practice on and essentially no practice benefit. Movements were not systematically biased toward one of the other transforma- tions. With the line-symmetric transformation, the initially poorer accuracy reached the level of the participants practising the point- symmetric transformation rather rapidly. Early in practice move- ments according to a point-symmetric transformation were observed. In a similar way the accuracy of participants practising the sliding-lever transformation caught up, but remained worse at the end of practice, nevertheless. With this transformation move- ments according to a point-symmetric transformation were again observed early in practice, and the movements remained biased toward the line-symmetric transformation. These findings support the notion that the acquisition of an internal model of a complex visuo-motor transformation proceeds in a progression of approxi- mations to the accurate internal representation. Ó 2012 Elsevier B.V. All rights reserved. 0167-9457/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2012.01.004 ⇑ Corresponding author. Address: IfADo – Leibniz Research Centre for Working Environment and Human Factors, Ardeystrasse 67, 44139 Dortmund, Germany. Tel.: +49 231 1084301; fax: +49 231 1084340. E-mail address: heuer@ifado.de (H. Heuer). Human Movement Science 31 (2012) 1056–1070 Contents lists available at SciVerse ScienceDirect Human Movement Science journal homepage: www.elsevier.com/locate/humov