In Beside Ourselves, Naomi Quenk (1993) makes the case that during periods of extreme stress the inferior function takes control of consciousness and results in a person exhibiting uncharacteristic, childish, immature and archaic behavior. Quenk's model does not address the impact of stress at less than extreme levels. The Kirby and Barger (1996) model suggests that the inferior function does not take control but, rather, the person attempts to use the dominant function more adamantly as stress increases. They state that the greater the stress, the greater the effort to utilize the dominant function, which eventually results in a dysfunctional state. The stress model presented by Ware, et. al., (1994) suggests that under stress, type preferences migrate toward I, S and T.
My research and anecdotal evidence over the past 12 years using The CommunicationWheel and a systems model of typology suggests that as stress increases, the auxiliary, tertiary and fourth functions tend to rotate into consciousness in a sequential manner (see Figure 1). That is, at moderate levels of stress a low-level, stressed-out version of the auxiliary moves into consciousness. At high levels of stress, a moderately stressed-out version of the tertiary function moves into consciousness. If the stress increases to an extreme level, the fourth function will manifest as the inferior function, resulting in the appearance of a person's "evil twin, Skippy."