As for the large portion of liberals found in this study I would say it is more attributed to the suspicion of Psychology in the conservative sector..meaning..fewer conservatives see it as an viable science to study.
The science itself does not have an ideology, it is just a compilation of theories and tools about the workings of the mind and more recently the physiological workings of the brain.
Conservatives still have a flesh and blood brain..they just use it differently after years of maturity and experience. Many of the foundational studies and theories fall short because they focus on the younger years of development..even though as time has passed, we live decades longer. The science is still very much incomplete..like all other science.
Psychological “science” (1 Tim 6:20), too often, is based on false [worldly] assumptions.
This is why many Americanists [conservatives] are suspicious of it.