The report did not specify the financial terms of the deal.
The tech giant's plans for Emotient were not immediately clear, the Journal reported, confirming the news with an Apple spokesperson.
Emotient's software reads the expressions of individuals and crowds to gain insights that can be used by advertisers to assess viewer reaction, or by medical practitioners to better understand signs of pain in patients.
San Diego-based Emotient previously raised $8 million from investors, including Intel Capital, the Journal said.
Last month, Tesla Motors Chief Executive Elon Musk and other prominent tech executives announced $1 billion in funding for an artificial intelligence non-profit called OpenAI.
Apple and Emotient did not immediately respond to requests for comment.
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