Effects of injustice sensitivity and sex on the P3 amplitude during deception

• We investigate the P3 as an indicator of stimulus salience in a deception task.
• Deceptive knowledge is more salient than non-deceptive knowledge.
• Deceptive knowledge is more salient for women with higher injustice sensitivity.
• Sex and sensitivity to injustice modulate salience effects during deception.

In deception tasks, personality traits like the sensitivity to injustice (SI) modulate the P3 amplitude, which is an indicator of stimulus salience. Based on findings that demonstrated women to be more injustice sensitive than men, we expected sex to modulate effects of SI in deception tasks. We analyzed the P3 amplitudes of 57 participants in a deception task that comprised probe, target, and irrelevant pictures. Larger P3 amplitudes occurred for probes (known pictures that required deceptive responses) than for irrelevant pictures (unknown pictures that required truthful responses). Women with higher SI scores demonstrated larger P3 differences between probes and irrelevant stimuli. The findings suggest that women and men have different ways to process ethically-salient information and that SI modulates stimulus salience during deception. The effects of sex and personality have implications for the linkage between forensic psychophysiology and psychological assessment, because assessment is often based on individual differences.