Table 1. Overview of test conditions.
| Condition | Number of trials per session/criterion | Number of dogs testeda |
|---|---|---|
| pretrials | 3 trials/3 correct choices | 42 |
| standard visible displacement | 10 trials/at least 7 correct choicesb | 42 |
| control | 10 trials/no criterion | 36 |
| A-not-B error | 9 trials/at least 7 correct choices and no more than 1 A-not-B errorc. | 36 |
| original displacement device condition | 10 trials/at least 7 correct choicesb | 21 |
| simplified displacement device condition | 10 trials/at least 7 correct choicesb | 29 |
| visible displacement with final touch | 10 trials/at least 7 correct choicesb | 13 |
| visible displacement with initial sham-baiting | 10 trials/at least 7 correct choicesb | 11 |
| invisible displacement | 10 trials/at least 7 correct choicesb | 2 |
| invisible displacement with final touch | 10 trials/at least 7 correct choicesb | 2 |
Note. For detailed descriptions of conditions see text, for example trials see supplementary videos.
a
Sample sizes decrease across conditions for two reasons: 1) some dogs did not return for testing in later sessions due limited owner availability (N=19); and 2) some dogs failed to reach criterion in one condition and were not tested in subsequent conditions (N=21).
b
one-tailed binomial test with chance probability at 0.33: p < .02
c
an A-not-B error was counted when a dog made an incorrect choice in the first trial after the baited location had been changed, and chose the box that had been baited in the immediately preceding trials.