The general pattern of study findings is that the imposition of harsher sentences has either no effect on the rate of recidivism, or it has an adverse effect. This emerges from the literature reviewed by Martinson, Gibbs, and Greenberg, and is confirmed by such sophisticated studies as those of Gottfredson et al. and Beck and Hoffman. The most frequently offered explanation for this finding is that harsh sentences, and in particular prolonged terms of imprisonment, have the harmful effect of stigmatizing the offender and internalizing the norms and values of the prison subculture, rendering the offender virtually incapable of reintegration into society. Another explanation is that when a prisoner has been in prison for some months, he/she becomes dulled to its conditions, such that the length of time under such conditions is not experienced as more severe punishment. Thus, the evidence suggests that severe sentences neither increase the likelihood that the offender on whom the punishment is imposed will be deterred from further crime, nor, because of the probable adverse effects of increasing severity on certainty of punishment (studies show that certainty of punishment tends to decrease with an increase in severity of punishment, perhaps because of a greater reluctance to convict under harsher penalties), do they result in an enhanced deterrent effect on the potential offender. It thus seems possible that in some situations deterrence is more likely to be achieved by reducing penalties and increasing the certainty of punishment, rather than by increasing penalties. A total of 163 footnotes are listed.