2020-2025: Truly functioning lie detectors are invented, as opposed to today's useless polygraphs.
2025-2030: The use of functioning lie detectors becomes more widespread. It is discovered that people often pretend to be unable to help their actions due to social pressure, even if they actually could help their actions. The people on whom this, by accident, was first discovered fall victim of hatred campaigns. They are shunned in society, making them feel bad. Governments use this to conceal the campaign to destroy their brains as "necessary" involuntary committment.
2030-2040: As the use of functioning lie detectors continue to spread, it gradually turns out that most people pretend (or by then, used to pretend) to be unable to help many of their actions. But by then, so many people have been brain damaged by psychiatric drugs and electroconvulsive therapy, the population majority can no longer help their actions. Psychiatry's "correction" of the few remaining people who can help their actions intensifies.
2040-2060: As almost all people have been reduced by psychiatry to zombies, they start to adopt the view that the genetic ability to help one's actions is sexually unattractive. Some governments even order sterilization of those who could help their actions prior to their involuntary committment. The individuals that never had the genetic ability to help their actions procreate the most, and the number of children born with the genetic ability to help their actions start to decrease. There are still some left, though psychiatry reduces them to zombies too and registers them as genetically capable of helping their actions.
2060-2800: Selective breeding against the ability to help one's actions continues. Since the genetic variation already exists, evolution does not have to wait for new mutations. Therefore selection can act in mere centuries instead of having to wait for hundreds of thousands or even millions of years for new genetic diversity to form. The ability to help one's actions dies out, and humanity no longer exists as intelligent life.
2800-3000: The stupid animal descendants of humanity continue to monkey see monkey do language and technology for a while. But without the ability to be influenced in one's actions by arguments, the use of arguments loses its function by the principle that parasites without hosts cannot exist. Language dies out like feral parrots cut off from human contact lose words for each generation and becomes totally speechless in 200 years. With it, most technology also disappears. Without critical thinking, the way of making simple tools is not questioned. Technology regresses into and stabilizes at tools similar to those Homo erectus made unchanged for more than a million years.
3000 and beyond: Stagnation, stagnation, stagnation...