Dateline: January, 2007, Issue 4
The jurors in the Scott Peterson trial recommended the death penalty, and afterwards commented that Scott Peterson looked "cold and unemotional" during the trial. Did Scott Peterson's demeanor affect jurors' recommendation of a death sentence?
Two recent research studies report that emotionally impassive defendants are convicted more often and punished more severely.
Heath and Grannemann (2004) studied how the amount of emotion displayed by a defendant influenced conviction rates. A defendant displaying a low, as opposed to a moderate or high, level of emotion was judged more guilty and less credible, although only when the evidence against the defendant was weak. When the evidence was strong, the defendant's emotional display had no effect on the conviction rate. When the evidence was weak, a stronger display of emotion by defendants was associated with fewer guilty verdicts, shorter sentences, and perceptions of a more honest defendant.
Antonio (2006) studied how a defendant's emotional involvement during trial influenced sentencing recommendations in death penalty cases. A defendant's demeanor affected whether jurors recommended the death penalty or life in prison without the possibility of parole. When a defendant appeared emotionally involved during the trial (i.e., sorry and sincere), jurors either favored a life sentence or were undecided about punishment. When a defendant appeared emotionally uninvolved (i.e., bored), jurors either sought a death sentence or remained undecided. An defendant's impassive demeanor resulted in a harsher recommended sentence.
In sum, jurors find unemotional defendants guilty more often, and punish them more severely.
Source Heath, W. P., Grannemann, B. D. & Peacock, M. A. (2004). How the defendant's emotion level affects mock jurors' decisions when presentation mode and evidence strength are varied. Journal of Applied Social Psychology, 34, pp. 624-664.
Source Antonio, Michael E. (2006). Arbitrariness and the death penalty: How the defendant's appearance during trial influences capital jurors' punishment decision. Behavioral Sciences & the Law, 24, pp. 215-234.