All we need is a little light, more or less

The Hawthorne effect has been discussed in business management meetings for a long time. The story went that increasing the amount of illumination in a factory increased productivity, but that reducing illumination (to a still reasonable level) also increased productivity. Managers and other story-tellers believed that workers were responding to the increased attention given to their work. ("Someone cares about me.") Turns out, what we believed wasn't so.
Put this into the same bin as frog-boiling.