Table 2 Scoring of startle response upon exposure to the novel object (within the first three seconds).

From: Behavioural responses to unexpected changes in reward quality

0 moves away from the novel object
1 passive (no reaction in the first 3 s, only looking)
2 walks around to look at toy from a different angle but does not move closer than 1 m within the first 3 s
3 approaches hesitatingly to within 1 m
4 approaches toy immediately to within 1 m