When facial cues aren't enough, there's Shippo.
A concentrating person emits brain waves in the range of 12 to 30 hertz, while a relaxed person's waves measure in the 8- to 12-hertz range, NeuroSky, the San Jose-based company that developed the Necomimi, told CNET.
With Shippo, relaxed users' tails will demonstrate "soft and slow" wagging, while concentrated users' tails will display "hard and fast" wagging. The gadget is also social media enabled; a neural application reads the user's mood and shares it to a map.
But does the Shippo tail work? This entertaining video promo certainly makes it seem so. Unfortunately, since the project is only in its prototype phase, there aren't any models available to test outside of the company's Tokyo office, a Neurowear spokesperson told The Huffington Post in an email.
As HuffPost Tech's review of the Necomimi explains, getting "in the zone" for the product to respond appropriately can prove difficult for some users (although not with our reviewer). It's conceivable that the Shippo may present similar issues.