Spatial asymmetries undermine also the short forms of the Judgement of Line Orientation test.

Objective: The Judgment of Line Orientation (JLO) test is one of the most used tasks for the assessment of visuospatial perception. However, JLO items show a left-right structural asymmetry that interacts with the ipsilesional attentional biases of brain-damaged patients, that is, the main target population for which the test is intended, and undermines the test's validity. Left hemisphere-damaged patients are favored by the way the stimulus lines are distributed in the original items, whereas right hemisphere-damaged patients are favored by the opposite distribution, obtained by mirror reversing the items (Treccani, Torri, & Cubelli, 2005). Here we aimed to analyze the short forms of JLO available in the literature, which are often presented as preferable alternatives to the full form.

Method: Characteristics of the items of these short forms were scrutinized. By reanalyzing data from Treccani et al. (2005), we also investigated the impact of these characteristics on brain-damaged patients' performance.

Results: Seven of the 8 analyzed short forms proved to be even more asymmetric than the full form (e.g., they have a different number of left and right lines), whereas the remaining one, which uses a flexible item-selection criterion, leads to unpredictable results. Like in the full form, these asymmetries affect brain-damaged patients' performance.

Conclusions: The presence of spatial asymmetries in JLO items cannot be neglected anymore in the development of any JLO form, given their impact on performance and the resulting detrimental effect on the accuracy and validity of the measurement. We propose to select 5-10 items among those of the original set and present them together with their mirror images to obtain a left-right balanced JLO short version. (PsycINFO Database Record (c) 2019 APA, all rights reserved).