Mean heart rate was the most precise physiological measure for these tests, and walking and defecation frequency were the most precise behavioural measures for novel stimulus and isolation tests, respectively.
In fact, it is likely that the degree of familiarity among the class of familiar stimuli (during encoding) was quite variable and that those stimuli whose encoding benefited most from reward were the least familiar (relatively most novel) ones.
The general method of learning was to pair an unconditioned stimulus (US) with a novel stimulus.
Both isolation and novel stimulus tests produced valid measurements.
In Experiment 1, participants completed two conditions, in one of which the over-selected stimulus was established, and then extinguished by pairing the over-selected stimulus with a novel stimulus and reinforcing the novel stimulus.
Four methods of ranking horses on reactivity were evaluated and compared: isolation from conspecifics, presentation of a static novel stimulus, traversing a novel stimulus in a runway (isolation, novel stimulus and runway tests, respectively) and assigning subjective emotionality scores.
The results from our novel stimulus task, in which the illuminated pecking key changed colour, show that hand-reared birds were faster to peck the novel-coloured key; we therefore suggest that the most parsimonious interpretation of the autoshaping result is that the hand-reared birds were similarly less neophobic the first time they saw the stimulus in the autoshaping task.
Consequently, the novel stimulus for one trial became the familiar stimulus for the next trial.
The presentation of stimuli was pseudo-randomized so that all five deviants and one novel stimulus appeared once among 12 successive stimuli, and the same deviant or novel was never repeated after the standard stimulus following it.
Our findings however revealed a P3a that was larger to infrequent stimuli compared to novel stimulus at all midline electrodes.
