The method of training dogs in auditory recognition memory tasks with trial-unique stimuli

Three adults dogs were trained in a auditory recognition delayed-matching-to-sample (DMS) task. The experimental setting consisted of one central speaker located in front of the dogs head, two side speakers with nearby response pedals and one rotary food delivery system. Three hundred twenty natural sounds were used as trial-unique stimuli. Sample stimuli were always given through the central speaker. After the delay of 1.5 s, both sample and testing stimuli were activated alternately through the two side speakers. Bar-press response toward the sample stimulus was rewarded by food. The DMS training was continued until attaining a criterion 90% correct responses in 90 consecutive trials. After a control pause, the dogs were retrained to the criterion, and then they were given performance tasks with delays extended to 10-, 30-, 60- and finally to 90-s, in blocks of 90 trials. Dogs required about 1,000 trials of auditory recognition memory training in order to reach the criterion. Their behavior was also stable after the control pause. The dogs performance declined gradually with extended delays reaching an average of 63.4% for the delay of 90 s. Results indicate that the DMS task with auditory stimuli alternating during the testing stage of trial, is a promising method for testing auditory recognition memory.