A computer vision card reader and/or point of sale device is described. The device is configured to sense when a user inserts a card into a card reader and to determine when a user departs or is about to depart from the device without retrieving the card. The device may issue an audible or visible alert to the user, reminding the user to retrieve the card. The device may additionally send a notification to a mobile device associated with the user that reminds the user that he has left a card at the point of sale. In some embodiments, message sent to the user contains a code and, upon entry of the code, the point of sale or card reader device returns the card to the user.