An overview of previous handedness research and a critical assessment of methods, results, and theories of this research are presented. The results of this assessment challenge the current experimental and theoretical approaches. Subsequently a new model of handedness is presented. This model is made up of four elements: (a) Handedness is associated with innate and genetically coded brain asymmetry. (b) The functional representation of handedness of left- and right-handers is mirror reversed. (c) The actual specification of handedness is determined in a random process. (d) The distribution is U-shaped with approximately 50% left-handers and 50% right-handers. The innate disposition of a majority of left-handers is changed by environmental influence, by practicing right hand writing, and by right hand tool use. Switching handedness causes differences between switched and nonswitched left- and right-handers or between left and right hand writers regarding psychological characteristics and related neuronal and physiological features. It is argued that the existence of such differences indirectly supports the new model. The alternative handedness model explains and integrates results of previous research, which do not correspond to current models and theories. Finally, ideas and considerations for an alternative approach of testing handedness are presented.

Ein deutschsprachiger Abstract liegt nicht vor, da die Arbeit in Englisch abgefasst ist.