Ganel et al. (2012, PLoS One) reported that when participants discriminated between two discs (40 and 40.5 mm in diameter), grasping was more accurate than perceptual judgements, thereby suggesting that visual information is differently processed for perception versus action in the ventral versus dorsal cortical streams (Perception-Action Model). The basis for this interpretation was that participants’ grip apertures during grasping reflected the true size difference of the discs well, while perceptual judgement accuracy was only 59% (close to chance-level of 50%). However, interpreting such a pattern of results as a difference in accuracy (good accuracy in grasping vs. bad accuracy in perceptual judgement) has been criticized for other experimental paradigms: Meyen et al. (2021, JEP:G) showed that the same underlying information can result in poor classification accuracy, yet show a clear separation of the means (e.g., in grip apertures). Instead, they suggest to dichotomize the continuous measures (grip apertures) using signal detection theory to calculate a corresponding (grasping) classification accuracy. The planned experiment will be an improved replication of Ganel et al. (2012) with n = 36 participants. Further, grasping classification accuracy will be calculated and compared to the perceptual judgement accuracy. Therefore, differences in the ability to discriminate size in grasping versus perception will be directly tested. Additionally, the experiment will also include a manual size estimation task, which is assumed to rely on perceptual representations but has similar task demands as grasping for better comparability.