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Sir,

I read with interest this article [1]; the authors highlight the importance of aptitude testing and ‘good spatial awareness’ for surgery, but especially for laparoscopic surgery. Spatial awareness or visual-spatial ability is clearly a subject that generates many misunderstandings. Several surgeons are loosely applying this term as a method for selecting future candidates. However, this is an over-simplification; visual-spatial ability refers to the human visual system's processing of image properties so that three-dimensional information can be extracted from the two-dimensional image that is projected onto the retina. It has been suggested that there is a hierarchy of visual-spatial ability: (i) edge and surface extraction; (ii) edge-orientation encoding; (iii) whole object recognition; (iv) spatial relations of object parts in two dimensions; and (v) images that involve two-dimensional and three-dimensional whole-object spatial rotations and translations [2,3].

That there is a link between visual-spatial ability and surgical skill is itself tenuous. Current research suggests that all surgical tasks involve low-level visual processing, e.g. object edge extraction, but the ability to visualize an end product before initiating a procedure is likely to involve higher level visual-spatial processing. A recent study used visual-spatial ability ranging from low- to high-level visual processing, and assessed competency in a spatially complex surgical procedure. They found that trainees with a high score did significantly better in the procedure than those with lower scores. However, the latter group achieved a comparable level of competency with practice and feedback [4].

The conflicting results that emerge from research in visual-spatial ability reflect the complexity of the subject. There are many visual-spatial tests available and to date there has been little justification for the use of a particular test; many studies have not used objective measures of surgical skill, and many researchers have failed to use a homogeneous group of trainees, i.e. trainees perform too many and varied surgical tasks to establish any relationship with visual-spatial ability. Thus we are a long way from using any visual-spatial test for selection or aptitude testing. In the first instance, each speciality needs to determine specific tasks with measurable constructs, and then establish visual-spatial tests that parallel these measurements.