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In a first pre-registered experiment (detailed at length here: https://osf.io/jtsuf) conducted on healthy participants, we studied the effect of spatial attention on the line bisection and visual vertical tasks. We found that shifting spatial attention to the left or the right by means of exogenous visual cues could bias the subjective line midpoint (in the line bisection task), as classically reported in the literature (e.g., Sosa et al., 2011). In contrast, this intervention had no significant effect on the subjective vertical. The first goal of the present experiment will be to replicate these results, by using the same methodology. The second goal will be to generalize our results and test the effect of spatial attention on egocentric spatial processes as measured by the straight-ahead task. We will test whether the eventual presence of egocentric biases (subjective straight-ahead) are correlated with the allocentric biases (subjective line midpoint) observed in the line bisection task. In this second experiment, we will thus add a visual straight-head task to the protocol and test the effect of the visual lateralized cue on this task. In a third experiment, we will ask healthy participants to perform (only) a proprioceptive straight-ahead task, during which continuous auditory cues will be presented to the left or right of the participant. This control experiment will eliminate the possible confounding effect of visual saccade on the subjective straight-ahead measured in Experiment 2. In experiment 2, visual straight-head deviation induced by the presence of the visual cue could in fact be due (at least in part) to eye deviation toward the cue. If the modulation of spatial attention is not modality-specific, Experiment 2 and 3 should yield similar egocentric biases induced by the cue.