The emotional valence of a situation can modulate selective attention. The valence of training experience is crucial for horses, the use of a positive reinforcement as a food reward has been shown to enhance learning performances and to promote a positive relation to the trainer. Here, we investigated the impact of different reinforcement (no reinforcement, primary positive reinforcement) or action (scratch the wither) on the horses’ attentional state in a learning task. In a first study, 15 young males Angloarabian were trained to remain still in response to a vocal command. Immobility was rewarded either with a piece of food (n=8) or with no reward (n=7). In a second study, 15 young polish horses (6 females, 9 males) were trained to the same task, but here, immobility was rewarded either with a piece of food (n=8) or with a tactile contact (scratching on the withers during 5 seconds, n=7). For both studies, monitoring, gazes and behaviours directed towards the trainer revealed that the use of a food reward as positive reinforcement increased horses’ selective attention towards their trainer (MW, P<0.05 in all cases). These studies suggest that attention may well be the process underlying the efficiency of appropriate reinforcements leading to better learning performances. This also explains increased bonding in human-animal training situations when positive emotions are involved. Horse attentional state is a key for better interaction, better security and better performances in a working situation. Nevertheless, only individuals can tell what an appropriate reward is and which reward induces positive emotions and hence triggers attention.