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TWO-SCALE POINTING : AN EVALUATION OF FOUR GRAPHICAL USER INTERFACE ALTERNATIVES The graphical user interfaces of today’s computers create a new context in which the classic issue of aimed movement can be tackled, especially in the case of highly difficult tasks. A new feature is that pointing often involves two successive phases. The first phase consists of macro-pointing (bringing the view into the vicinity of the target, the document providing the global frame of reference of the movement), whilst the second consists of micro-pointing (bringing the cursor to the target, now visible in the local frame of reference of the view), with the macro component of pointing representing an increasing proportion of movement time as task difficulty is scaled up. Focusing on movement time, we investigated two-scale pointing in four categories of interface (with traditional scrollbars, with direct manipulation of separate and integrated spatial dimensions, with one and with two hands). Our data show that the efficiency of the widely spread scrollbar device is limited, presumably because it precludes direct manipulation of the document. We also show that, with direct manipulation of the document, performance improves when the XY  dimensions are integrated, rather than separated. Finally, we evaluate and discuss the impact on performance of separating the two components of the task between the two hands (macro-pointing to the non-preferred hand and micro-pointing to the preferred hand).