Here are some of the reasons for our hypothesis:
There is a substantial amount of evidence that the processes underlying face recognition (for example, recognizing your friend's face) and the processes underlying basic-level object recognition (for example, recognizing a stimulus as being a table, a chair, etc.) are different. For example, functional neuroimaging techniques have shown that different areas of the brain are active during facial recognition than are active during basic-level object recognition. Additional evidence comes from the study of brain damaged patients. There are some brain-damaged patients who are impaired at recognizing faces but show intact basic-level object recognition. Other patients show the reverse trend of intact face recognition but impaired basic-level object recognition.
Laterality studies also provide evidence that the processes of face recognition and object recognition use different areas of the brain. Laterality studies find a strong right hemisphere advantage for recognizing faces. basic-level object recognition, on the other hand, fails to show a marked right hemisphere advantage. These findings argue strongly that different neural substrates underlie the two tasks.
What does all this have to do with the recognition of plants and animals? As it turns out, many of the people who have localized brain damage resulting in impaired face recognition also have problems recognizing certain types of plants and animals. Furthermore, another experiment conducted in our lab has shown an interesting dissociation between recognizing animals and basic-level objects (click here to see this experiment). These findings suggest an underlying commonality to the process of recognizing faces, plants and animals. To provide converging evidence for this commonality, we are conducting a laterality study. Our hypothesis is that plants and animals will be recognized better when they are presented visually to the right hemisphere of the brain while other basic-level objects will not show the marked right hemisphere advantage.
Click here to see how we are carrying out our laterality experiment.