Ontogeny
Figure 4. Tonic immobility (TI) duration of hens in two trials, on slats and on litter. Group means are presented. (Corticosterone is a stress response hormone.)
Inducing the state more frequently in chicks can affect their behavior as adults.
Unlike other forms of thanatosis, tonic immobility is believed to be an involuntary reflex, most demonstrated in instances of stress. Because of this, there is minimal research that looks at the development of the behavior in any animal. However, some research has been conducted to show correlation between the behavior, or in this case the rate at which chickens exhibit tonic immobility over time.
A study looked at the development of tonic immobility throughout the lives of chickens (El-lethey 2001). Plucking feathers is extremely stressful, and plucking them at a young age has been found to increase the length and frequency that chickens entered a tonic state throughout adulthood. This indicates that an increase in stress at a young age can later influence how animals react to stress in adulthood, at least in the case of tonic immobility (El-lethey 2001). This study is one of the few that looks at influences on the development of the behavior throughout a lifespan.