Self-bias effect: movement initiation to self-owned property is speeded for both approach and avoidance actions

Recall of, and physical interaction with, self-owned items is privileged over items owned by other people (Constable et al. in Cognition 119(3):430-437, 2011; Cunningham et al. in Conscious Cognit 17(1):312-318, 2008). Here, we investigate approach (towards the item), compared with avoidance (away from the item) movements to images of self- and experimenter-owned items. We asked if initiation time and movement duration of button-press approach responses to self-owned items are associated with a systematic self-bias (overall faster responses), compared with avoidance movements, similar to findings of paradigms investigating affective evaluation of (unowned) items. Participants were gifted mugs to use, and after a few days they completed an approach-avoidance task (Chen and Bargh in Pers Soc Psychol Bull 25(2):215-224, 1999; Seibt et al. in J Exp Soc Psychol 44:713-720, 2008; Truong et al. in J Exp Psychol Hum Percept Perform 42(3), 375-385, 2016) to images of their own or the experimenter's mug, using either congruent or incongruent movement direction mappings. There was a self-bias effect for initiation time to the self-owned mug, for both congruent and incongruent mappings, and for movement duration in the congruent mapping. The effect was abolished in Experiment 2 when participants responded based on a shape on the handle rather than mug ownership. We speculate that ownership status requires conscious processing to modulate responses. Moreover, ownership status judgements and affective evaluation may employ different mechanisms.