Robot Pain

Introduction

Is robot emotion possible? Currently, there are two main programs of scientific research investigating this question. One main line is a type of psychological behaviorism and assumes that emotion behavior can be explained in a robot without reference to subjective or mental events or states. According to this approach, the sources of robot emotion are exogenous (in the environment), not endogenous (in the head) (e.g., Adolphs, 2005; Canamero, 2005; Dautenhahn et al., 2009; Picard, 2000). Much work in this research program aims to build able robots to display emotional sensations behaviorally under specific circumstances without sensing them endogenously, or robots that attribute sensations to human beings based on visual observation of behavior rather than empathic understanding, conceived as an endogenous state type shared at the time of observation.

Behaviorist robot emotion faces several challenges. One challenge is that some subjective features of sensations have qualitative character, or 'qualia', broadly characterized as the properties of sensation states that type them in qualitative or sensed aspects (e.g., Chalmers, 1996; Jackson 1982; Tye, 2000). Type states of pain differ in sensed qualities from type states of pleasure, or in 'what it is like' to personally experience them. Thus, to have a pain is not only to produce appropriate pain behavior under certain circumstances, but it is to personally experience a 'like-this' sensory quality to the pain (e.g., as something burning or sharp). Two subjects in a psychophysical experiment presented with the same stimulus and showing the same behavioral responses may nonetheless have quite different qualitative experiences. Stimulus-response identity does not entail experiential identity, and such identity cannot be ensured other than by describing the experiential states and how these are experienced. In the same way, a purely behaviorist robot may display pain behavior, yet completely lack pain qualia.

Some philosophers claim that what is definitive of individual sensation qualia ('quale') is functional role, described as the causal relations a sensory quale type has to stimuli, behavior and other subjective states (e.g., Armstrong, 1968; Fodor, 1975; Lewis, 1966; Maley & Piccinini, 2013; Putnam, 1975; Pylyshyn, 1984; Shoemaker, 1984). A role functionalist may define a pain as a sensory qualitative state that is reliably caused by noxious stimulation, to cause the desire to make it stop, to cause distraction regarding concurrent projects or plans and their completion, and to cause changes in preferences among alternative states of affairs. According to role-functionalism, only beings with subjective qualitative states that fulfill these causal roles can be in pain.

In normal adult humans, there appears to be a specific type of nervous-endocrine-immune biological activity that best fits these functional roles (van Rysewyk, 2013). Thus, normal humans can be in pain by noxious stimulation of the nervous-endocrine-immune ensemble. Since sensations that are physically very different may still feel the same, role-functionalism allows beings with different physical compositions to have sensory qualitative states as well. If there are biological states of feathered mites or non-biological states of robots that also fit these roles, then these beings can be in pain. Pain qualia can be realized by multiple types of physical states in multiple types of beings (e.g., Aizawa, 2008; Fodor, 1975; Putnam, 1975; Pylyshyn, 1984).