Obligatory integration of face features in expression discrimination

Previous composite face studies have shown that an unattended half differs in identity or expression from the attended distracts perception. These typically not controlled for amount of information different halves. We investigated feature integration while participants discriminated angry and happy expressions. The stimuli were scaled using individual thresholds to control strength In first experiment, we varied relative upper lower parts. second tried ignore one face, which was either congruent incongruent with half. found both beneficial obligatory A robust effect when attending eyes mouth, expressions, suggesting similar processing halves is for.