negativistic

noun

1. a negative or pessimistic attitude.
2. Psychology. a tendency to resist external commands, suggestions, or expectations, or internal stimuli, as hunger, by doing nothing or something contrary or unrelated to the stimulus.
3. any system of negative philosophy, as agnosticism or skepticism.

noun

1. a tendency to be or a state of being unconstructively critical
2. any sceptical or derisive system of thought
3. psychiatry refusal to do what is expected or suggested or the tendency to do the opposite

n.1824, “the policy of opposition;” see negative + -ism. In a psychological sense, it is attested from 1892. n.

1. A tendency to do the opposite of what one is requested to do, or to resist stubbornly for no apparent reason.