Signal detection on the battlefield: priming self-protection vs. revenge-mindedness differentially modulates the detection of enemies and allies

Abstract

Detecting signs that someone is a member of a hostile outgroup can depend on very subtle cues. How do ecology-relevant motivational states affect such detections? This research investigated the detection of briefly-presented enemy (versus friend) insignias after participants were primed to be self-protective or revenge-minded. Despite being told to ignore the objectively nondiagnostic cues of ethnicity (Arab vs. Western/European), gender, and facial expressions of the targets, both priming manipulations enhanced biases to see Arab males as enemies. They also reduced the ability to detect ingroup enemies, even when these faces displayed angry expressions. These motivations had very different effects on accuracy, however, with self-protection enhancing overall accuracy and revenge-mindedness reducing it. These methods demonstrate the importance of considering how signal detection tasks that occur in motivationally-charged environments depart from results obtained in conventionally motivationally-inert laboratory settings.

Figure 1. Figure 1a shows bias as a function of target gender and ethnicity, collapsed across facial expression.

While there is a bias to see Arabic men as “enemies”—and this bias becomes more pronounced in both the self-protection and revenge conditions—there is an even greater bias to call ingroup members “friends”, which entails missing more ingroup enemies. Figure 1b depicts bias for faces showing slight anger (collapsed across target gender), and clearly shows that self-protection and revenge wipe out the bias to call angry ingroup members “enemies”: In the control condition there is a strong bias to call any angry face an enemy, but both self-protection and revenge conditions completely eliminate this bias for ingroup faces. Figure 1c shows participant accuracy in discriminating between enemies and friends.