Final answer:
Martin Seligman is the psychologist who worked with dogs in experiments that led to the proposal of the learned helplessness theory, which later evolved into hopelessness theory.
Step-by-step explanation:
The theorist who worked with dogs and proposed the theory of learned helplessness was psychologist Martin Seligman. In conjunction with his colleagues, Seligman conducted a series of experiments in the late 1960s that demonstrated the phenomenon of learned helplessness using dogs. These dogs, after being subjected to inescapable shocks, failed to attempt to escape from the shocks even when it was later possible to do so. They had essentially learned to be helpless, believing that they had no control over the situation. This behavior in the dogs was used to draw parallels to human depression, theorizing that a similar response to uncontrollable negative events might contribute to depressive symptoms in humans.
Notably, Seligman and his colleagues would later reformulate their theory, focusing more on attributions and thinking patterns that contribute to feelings of helplessness and subsequent depression. This evolution of learned helplessness into what is now known as hopelessness theory remains a significant aspect of understanding depressive disorders.
It is important to differentiate Seligman's work from that of Ivan Pavlov, another well-known scientist who also worked with dogs but in the field of classical conditioning, paving the way for behaviorism as a model for understanding behavior.