““Adding variability increased the frequency of the pigeons completing the intended action. Skinner’s pigeons tell us a great deal about what helps drive our own behaviors. More recent experiments reveal that variability increases activity in the nucleus accumbens and spikes levels of the neurotransmitter dopamine, driving our hungry search for rewards.[lxxiv] Researchers observed increased dopamine levels in the nucleus accumbens in experiments involving monetary rewards as well as in a study of heterosexual men viewing images of attractive women’s faces.[lxxv] Variable rewards can be found in all sorts of products and experiences that hold our attention. They fuel our drive to check email, browse the web, or bargain-shop. I propose that variable rewards come in three types: Tribe, hunt and self (figure 20). Habit-forming products utilize one or more of these variable reward types.””
