GMAT Sentence Correction (SC) | Re: In recent years scholars of psychology have begun

Note : in this sentence we have to use present perfect tense which will have a construction like this
Have+ past participle of begin

Begin: base form
Began: used in past tense
Begun: past participle

So the use of began will be incorrect. Began cannot be used here..

For more on past participles of unusual verb form...check out mgmat sc..
You can also use the below link