Yes, a self-employed psychologist can take the QBI depending on the income.
The specified service trade or business (SSTB) classification doesn’t come into play as long as total taxable income is under $157,500 ($315,000 if filing jointly). At higher income levels, the deduction for SSTBs is reduced and in some cases, eliminated.
Psychologists are covered by the above classification, but the QBI is available until they reach the above income thresholds.
For more information, follow this link: https://ttlc.intuit.com/questions/4499030-what-is-the-qualified-business-income-qbi-deduction
