Four positive stimuli were presented to the dogs, two food stimuli and two social stimuli.

The stimuli were thought to be percieved with two levels of positivity, with one food and one social stimulus to be percieved as very positive and one food and one social stimulus to be percieved as less positive (still positive, only less positive than the very positive stimulus)

The stimulus was presented to the dog from a stimuli theatre.

In the upper part of the theatre, a small square was cut out and the stimulus was presented on a shelf at the base of this square. The theatre was also equipped with a sliding shutter pulled with a string. When the shutter was closed, the shutter covered the cut out square and the stimulus was hidden from the dogs, and when the shutter was opened, the stimulus was visible for the dogs.

The lower part of the theatre was replaced with black fabric and enabled the dogs to recieve the stimulus as a reward after the presentation.

The food stimuli was given with a forceps while the social stimuli in person greeted the dog.

The testing arena included the stimuli theatre, a start cage and an experimental cubicle.

The dog started the experimental session in the start cage and after being released, walked up the ramp and positioned herself in the experimental cubicle facing the theatre.

The dog stayed in the cubicle throuhout the entire stimuli presentation an after being rewarded, walked back to the start cage.

The experimental session and the presentation of the stimulus was divided into different phases. The dog was first positioned in the start cage for 10 seconds. While fully positioned in the cubicle, the shutter on the theatre was closed and the stimulus was hidden from the dog during five seconds. Following this, the shutter was pulled up and the stimulus was visible for the dog during five seconds. These two phases were then repeated once each. After the last phase (the second time the stimulus was visible) the dog received the stimulus. After the reward phase the dog went back to the start cage and a new stimuli presentation started (with a new stimulus).

The stimuli were presented to the dogs according to a balanced scheme, with all four stimuli being presented four times (one time each test day).

The ECG recordings started during the first visible phase and ended after the reward phase.