Must egocentric and environmental frames of reference be aligned to produce spatial S-R compatibility effects?

Four experiments were conducted to determine the effects of misaligning egocentric and environmental frames of reference on spatial S-R compatibility effects. In Experiments 1 and 3, subjects looked at two lights that were aligned horizontally, one each on either side of the body midline. They held their head upright or tilted 90 degrees to the left or right. In the upright condition the hands were uncrossed and rested opposite the lights (frames of reference aligned), whereas in the head tilt condition the hands were either crossed or uncrossed but positioned perpendicular to the lights (frames of reference not aligned). Manual choice reaction times to the lights produced spatial S-R compatibility effects that were as large when the frames of reference were aligned as when they were not. In Experiments 2 and 4, which also used upright and tilted conditions, we found generally similar results when the lights were displayed vertically and the hands disposed horizontally. The results indicate that under conditions of head rotation and with stimulus and response arrays perpendicular to each other, spatial S-R compatibility effects still occur. By taking into account both frames of reference, the subject classifies the stimuli as left or right whether they are horizontally or vertically disposed and maps them onto the responding hand, thereby producing the observed compatibility effects.