Assume that humans emit a field that suppresses the intelligence of other living things.
What would be the biggest economic, cultural, or political effect of the invention of a device which could alter these fields? 'Biggest' means the most lasting impact on the most people (some wiggle room, but it's about how this change could affect the entire human race, not how it could change one person's life completely.)
- Fields have harmonics. Sync'd harmonics can bolster relationships and improve mood, health, and intelligence, while unsync'd harmonics can do the opposite. Harmonics are very poorly understood, and follow no pattern (the only real known property is that it's symmetric - if you harmonize with them, then they harmonize with you.)
- Fields and sensitivity to fields can differ significantly from person to person, although humans are the only species which has any significant resistance to fields
- Fields can change over time, due to environment and actions (nature + nurture)
- Fields only interact with sentience. They have no effect on matter or the regular laws of physics. No telekinesis or teleporting or magical abilities.
- The intelligence/ability of an individual human is dependent on how strongly they can resist the field of others, how effectively their behavior drives them to avoid or eliminate those with conflicting fields, and how good they are at finding like-fielded individuals.
- Technology, culture, etc. are the same as current Earth prior to this invention.
- The device can alter fields, generate fields, nullify fields, etc. There is no theoretical limit on the size of such a machine or its power, just whatever limits exist on providing energy (the energy cost to make the field larger has geometric growth.)
- For a baseline on cost, a field shelter (prevents outside fields from coming in) capable of covering a normal house would only cost ~$10 a month in electricity to run. A shelter for a football stadium would cost several thousand dollars to run for a few hours.
NOTE: I'm leaving up the community wiki answer because I think that it will help show the effects the fields have prior to the invention of this device.