Table 3.
Effects of personality, corticosterone levels, and age of testing on performance in each cognitive task
| Response variable | Explanatory variables | Estimate | Permutation p-value |
|---|---|---|---|
| Problem-solving score | Personality 1 | 1.196 | 0.045 |
| Personality 2 | −1.192 | 0.190 | |
| Personality 3 | 1.788 | 0.070 | |
| Baseline corticosterone | −0.110 | 0.801 | |
| Stress-induced corticosterone | −0.076 | 0.544 | |
| Age at testing | −1.830 | 0.090 | |
| Max. seed discrimination efficiency | Personality 1 | 1.523 | 0.695 |
| Personality 2 | 5.124 | 0.200 | |
| Personality 3 | 6.447 | 0.298 | |
| Baseline corticosterone | 1.178 | 0.457 | |
| Stress-induced corticosterone | −0.591 | 0.408 | |
| Age at testing | 0.574 | 0.660 | |
| Detour-reaching score | Personality 1 | −0.008 | 0.892 |
| Personality 2 | −0.011 | 0.861 | |
| Personality 3 | −0.017 | 0.887 | |
| Baseline corticosterone | −0.039 | 0.300 | |
| Stress-induced corticosterone | 0.007 | 0.562 | |
| Age at testing | −0.005 | 0.855 | |
| Average number of errors (spatial memory) | Personality 1 | 0.328 | 0.584 |
| Personality 2 | −0.035 | 1 | |
| Personality 3 | 1.427 | 0.226 | |
| Baseline corticosterone | 0.481 | 0.337 | |
| Stress-induced corticosterone | 0.129 | 0.354 | |
| Age at testing | 0.613 | 0.421 | |
| Habituation 1 | Personality 1 | 0.125 | 0.514 |
| Personality 2 | −0.563 | 0.130 | |
| Personality 3 | 0.474 | 0.170 | |
| Baseline corticosterone | 0.099 | 0.513 | |
| Stress-induced corticosterone | 0.037 | 0.416 | |
| Age at testing (problem-solving hab.) | −0.104 | 0.740 | |
| Age at testing (spatial memory hab.) | 0.049 | 0.851 | |
| Age at testing (seed discrimination hab.) | −0.322 | 0.034 | |
| Habituation 2 | Personality 1 | −0.426 | 0.037 |
| Personality 2 | −0.127 | 0.653 | |
| Personality 3 | 0.228 | 0.485 | |
| Baseline corticosterone | 0.127 | 0.382 | |
| Stress-induced corticosterone | 0.005 | 0.927 | |
| Age at testing | −0.221 | 0.382 | |
| Habituation 3 | Personality 1 | 0.163 | 0.332 |
| Personality 2 | 0.494 | 0.08 | |
| Personality 3 | 0.011 | 1 | |
| Baseline corticosterone | 0.0382 | 0.755 | |
| Stress-induced corticosterone | −0.052 | 0.210 | |
| Age at testing | −0.184 | 0.357 |
Age of testing corresponds to the age at which budgerigars were tested in the cognitive task included as the response variable in each model. Personality 1: PC representing exploration and juvenile neophobia. Personality 2: PC representing Sociability. Personality 3: PC representing adult neophobia. Habituation 1: PC representing by social habituation to the problem-solving device, and individual habituation to the seed discrimination and spatial memory devices. Habituation 2: PC representing individual and social habituation to problem-solving device. Habituation 3: PC represented by social habituation to the spatial memory device. Five thousand iterations were completed in all models until the criterion was met (maximum of iterations was set at 10,000). Significant results are indicated in bold.