In natural systems, many animals organize into groups without a designated leader and still perform complex collective behaviors. Although individuals in the group may be considered equal, all the individuals differ in the traits each of them possess. Of particular interest is the idea of an individual's personality as it often plays a role in determining which individuals lead collective behaviors. Personality is, in part, developed and maintained by an individual's experiences. However, neither an individual, nor its environment remains unchanged. Therefore, there is a need for an individual to continue to gain new experiences to ensure that its information about itself and its environment are current. Since observations have shown that the effects of experience on personality can decay over time, we investigate the effects of this decay on the emergence of leaders and followers and the resulting success of a group's collective movement attempts. Results show that personality decay has a negative effect on the overall success of the group in collective movements as it prevents the emergence of distinct personalities, a necessary requirement for individuals to assume distinct leader and follower roles.

Many animals form large aggregations that have no apparent consistent leader, yet are capable of highly coordinated movements. At any given time, it seems like an individual can emerge as a leader only to be replaced by another. Although individuals within a group are largely considered equal, even individuals in a homogeneous group are different. Clearly individuals will differ based on traits like sex, age, and experience. Of particular interest is the idea of individuals differing in their correlated traits, or personality. Different personalities can arise via complex interactions between genes and an environment and are often shaped by individual experience. For example, one would generally predict that individuals characterized as "bold" would more frequently be leaders. However, if the environment changes, how do once successful leaders respond to failure and how do newly successful leaders emerge? Using a biologicallybased collective movement model, we demonstrate that a self-assessment mechanism using winner and loser effects is capable of producing transitory leaders who change roles in response to changes in the environment. Furthermore, simulations predict that this self-assessment mechanism allows the group to adapt to drastic changes in the environment and remain successful.