Since telepathic technology is not available, we're going to have to settle for detecting Peril indirectly. 

After brainstorming sensor possibilities it is clear that in at least some cases, Peril will be detected only once it has actually occurred.  In these cases, we have to settle for the Peril-Sensitive Sunglasses producing a reactive calming effect (due to blocking out the distressing sights) rather than a proactive one.  

However, in at least some cases the activation of the Sunglasses *will* be pre-emptive.  For example, your pulse might rise not as a result of actual Peril being presented, but in response to a "gut feeling" that you're not fully conscious of.  In these cases, the Peril-Sensitive Sunglasses will be proactive rather than reactive.

Best ideas for sensors so far: 

- Measure GSR (galvanic skin response - i.e. how sweaty you are; increase = under stress, therefore peril?)

- Measure pulse (increased pulse = possible peril imminent)

- Measure ambient sound / volume (loud noises = possible peril?)

- Measure ambient light levels (sudden lighting changes = possible peril?)

- Detect things being pointed at you? (big ?? here)