Up until now, the methodology to find out what TV viewers like — based largely on written surveys and machines with dials to indicate their degree of enjoyment — has been fairly primitive and, most likely, not very reliable. Comcast’s NBCUniversal and Viacom are now both trying to dig deeper using biometrics, including eye movements, facial reactions, skin sensors, heart monitors, and EEGs to monitor brain waves. Viewing measurement company Nielsen even bought a neuroscience firm, Innerscope Resesarch, to add these skillsets to its lab.

According to Reuters, both NBCUniversal and Viacom are opening labs to study TV viewers via infrared cameras to track a variety of biometrics. Viacom’s lab will include EEG measurements. Nielsen will add facial coding and biometrics to its current use of eye tracking and EEGs. “This is the closest to what’s going on inside your brain,” says NBCUniversal president of research/media development Alan Wurtzel.

The new processes are twice as expensive as focus groups, at $30,000 to $100,000 per study. The other issue is that nobody really knows for sure how to interpret the results.

“Just because their brain cells are lighting up during a commercial, doesn’t necessarily mean they are going to buy the product,” says Beth Rockwood, executive at Discovery, which is thinking about doing more neuroscience research. “They may simply find the commercial engaging.”

Hershey, which has been using neuroscience and biometrics for several years, still hasn’t drawn definitive conclusions. “I don’t think anyone is comfortable saying that this is going to translate into more sales,” says Hershey executive Andy Smith.

Even so, this newer kind of research resonates well with advertisers, especially as they struggle with online platforms for viewership and ad dollars. CBS chief research officer David Poltrack points out that this kind of research requires sensitivity, to avoid “making consumers feel used.”

“I think that we should all feel a little paranoid and a little manipulated by all of this,” he said. “This is a trust and if we do it right, we provide information and content that is valued.”