Target trials

The dogs’ performance in choosing the target object correctly was statistically significant (binomial test, p (Y ≥ 56 | n = 76, p = .5) < .001), with a group mean success rate of 73.7% (SD ±0.18) in 56 out of 76 trials. The remaining 26.3% of trials resulted in incorrect or no choices (Figure 4).

The maximum success rate was 100% and the minimum success rate was 50% (Table 4). Milo, Nero, Omi, and Uno performed significantly better than chance (binomial test, p (Y ≥ 4 | n = 4, p = .5) < .001; Figure 5). However, individual statistical significance was not observed in the remaining dogs. To ensure the reliability of the results, only dogs that retrieved the target object in at least two out of four trials were included in the analysis. One dog did not meet this criterion, therefore was excluded from the analysis.

Figure 4. Group dog performance in target object task by correct and incorrect/no choice target choices (out of 76 trials) of N = 19 typical border collies. Error bars represent ± SE.
Figure 5. Individual dog performance in target object task (out of 76 trials) of N = 19 typical border collies (*p<.001).

Object generalisation trials

Out of the total of 76 trials, dogs chose objects with the same texture as the target object significantly more frequently than objects with the same shape (binomial test, p (Y ≥ 33 | n = 76, p = .5) < .001). The dogs did not choose anything in 34 trials (Figure 6).

Further analysis using the chi-square test revealed a significant association between the choice of objects and their shape, texture, or no choice (Χ² (2, n = 19) = 15.82, p < .001). Pairwise comparisons with the Bonferroni correction showed that the frequency of texture-based choices (proportion = 0.45) was significantly higher than that of shape-based choices (proportion = 0.12) (X² (1, n= 19) = 13.73, p < .001). The frequency of texture-based choices did not differ significantly from that of no choice (proportion = 0.43) (Χ² (1, n = 19) = 0.015, p = 0.903).

Figure 6. Frequency of choice of objects showing the percentages of trials in which dogs chose objects according to shape, texture or made no choice (out of 76 trials) of N = 19 typical border collies in object generalisation trials. Error bars represent ± SD.