Table 2.
Empirical tests and observations supporting the thermal window hypothesis.
| Prediction | Confirmed | Species |
|---|---|---|
| (1) Yawning should increase with initial rises in ambient temperature | – Campos and Fedigan (2009) | – Capuchins (Cebus capucinus) |
| – Deputte (1994) | – Macaques (Macaca fascicularis) | |
| – Gallup et al. (2009, 2010b) | – Budgerigars (Melopsittacus undulatus)* | |
| – Gallup et al. (2011) | – Rats (Rattus norvegicus) | |
| (2) Yawning should decrease when ambient temperatures draw near or exceed body temperature | – Gallup et al. (2009) | – Budgerigars (Melopsittacus undulatus) |
| – Gallup et al. (2011) | – Rats (Rattus norvegicus) | |
| – Gallup and Eldakar (2011) | – Humans | |
| (3) Yawning should diminish at very low ambient temperatures (e.g., −10°C) | – Unknown | – None tested |
*
Indicates a replication of this effect in an independent sample of this species.