P. G. Zimbardo (1969) suggested "the expression of normally inhibited behavior" may have both positive and negative consequences. He expanded the proposed realm of factors that contribute to deindividuation, beyond anonymity and loss of personal responsibility, to include: "arousal, sensory overload, a lack of contextual structure or predictability, and altered consciousness due to drugs or alcohol," as well as "altered time perspectives...and degree of involvement in group functioning" Zimbardo postulated that these factors lead to "loss of identity or loss of self-consciousness," which result in unresponsiveness to external stimuli by the individual and the loss of "cognitive control over motivations and emotions." Consequently, individuals reduce their compliance with good and bad sanctions held by influences outside the group.