They ARE brain experts.
Yes, neuroscientists are also brain experts.
But do you believe psychologists, especially RESEARCH psychologists... have NOT studied encephelograms, MRI's, or any other brain study on neural activity, neural net patterns, speech and memory sections of the brain, or even conducted those tests or studies themselves, in order to study their OWN field and all of the issues, idiosyncrasies, etc... of how the human mind works?
I mean, seriously... think about that for a sec...
(Sorry about the all-caps... but I'm still emphasizing key words or key issues, as is my habit...).