In a manner consistent with or according to behaviorist principles; from a behaviorist perspective or methodology.
From behavioristic + -ally (adverbial suffix). The stacked suffixes create an adverb form indicating adherence to behaviorist theory or methodology.
Behavioristically is the kind of word that appears in dense academic papers—it's technically precise but sounds clunky, showing how adding suffixes makes words more exact but also more cumbersome.
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