A recent study by Kim and Biederman suggested that the source of the scene-facilitation effect was the lateral occipital cortex, or LO, which is a portion of the brain's visual processing center located between the ear and the back of the skull. However, the possibility existed that the LO was receiving help from the intraparietal sulcus, or IPS, which is a groove in the brain closer to the top of the head.
The IPS is engaged with implementing visual attention, and the fact that interacting objects may attract more attention left open the possibility that perhaps it was providing the LO with assistance.
While participants took the test, electromagnetic currents were used to alternately zap subjects' LO or IPS, temporarily numbing each region in turn and preventing it from providing assistance with the task.
All of the participants were pre-screened to ensure they could safely receive the treatment, known as transcranial magnetic stimulation (TMS), which produces minimal discomfort.
By measuring how accurate participants were in detecting objects shown as interacting or not interacting when either the LO or IPS were zapped, researchers could see how much help that part of the brain was providing. The results were clear: zapping the LO eliminated the scene-facilitation effect. Zapping the IPS, however, did nothing.
When it comes to providing a competitive edge in identifying objects that are part of an interaction, the lateral occipital cortex appears to be working alone. Or, at least, without help from the intraparietal sulcus.
|Contact: Robert Perkins|
University of Southern California