There is often a temporal relation in survival probabilities in life-threatening situations such as predator-prey encounters. As a situation intensifies or becomes more immediately dangerous, reflex responses usually dominate behavior, resulting in there being less time available to gather information for more complex processing by higher brain substrates. The only information to form a memory of such a threatening experience may be some neural code for 'avoid' (or a negative emotional attribute) and the context in which the experience has occurred. Hence, memory for aversive experiences may be more labile while reflexive responses to danger become much less labile to experimental manipulation as the severity of the threat increases. Natural selection may have preferentially acted on escape and avoidance responses such that plasticity to make decisions concerning other options in increasingly dangerous arenas may be much more limited. The possibility that time becomes a trade-off in an organism's attempt to more fully evaluate characteristics of a perceived threat underlies the 'temporal trade-off hypothesis'.