Can stimulus enhancement explain the apparent success of the model-rival technique in the domestic dog (Canis familiaris)?

The model-rival technique is a method of training whereby an animal learns the distinguishing features of a target object, such as name and colour, by observing a trainer and a potential competitor engage in conversation about these features. In this study the apparent effectiveness of the model-rival technique in training dogs to perform a selection-retrieval task by McKinley and Young [McKinley, S., Young, R.J., 2003. The efficacy of the model-rival method when compared with operant conditioning for training domestic dogs to perform a retrieval-selection task. Appl. Anim. Behav. Sci. 81, 357–365] was investigated to evaluate the hypothesis that simpler forms of learning may be responsible for the results. This was tested by repeating McKinley and Young's model-rival training method and comparing the results to those of training sessions devised to include different forms of stimulus enhancement of the object to be retrieved. These training sessions involved: minimal enhancement, during which the experimenters made no interactions with the target object; indirect stimulus enhancement, during which both experimenters switched their gaze between the dog and the target object; or direct stimulus enhancement, during which one of the experimenters held the target object. It was found that only the model-rival and direct enhancement methods resulted in a significant number of dogs successfully completing the selection-retrieval test. There was also evidence to suggest that with the direct stimulus enhancement training method dogs learned quicker than with the model-rival training method. It was concluded that dogs are able to learn to retrieve a named object in a selection-retrieval task as a result of simple stimulus enhancement, without necessarily understanding the complex cognitive processes which underpin learning in the model-rival process.