All in the mind or in the body

How to Solve the Mind–Body Problemby Nicholas Humphrey, Imprint Academic, 2000.$12.95 (v +112 pages)ISBN 0 907845 08 8Nicholas Humphrey begins this reprinted topical issue of The Journal of Consciousness Studies 1xSee all References1by presenting an essay on how to solve the mind–body problem. This initial chapter is followed by 10 chapters (from Clark, Dennett, Eilan, Ellis, Hardcastle, Harnad, Newton, de Quincey, Rovane, and Van Gulick) that review Humphrey's theory, with a final reply chapter from Humphrey ending this monograph. The first and last chapters will be emphasized in this review because they are the central topic of this monograph. Can one define consciousness and solve the mind–body problem in 15 pages? Doubtful, but Humphrey does present a stimulating non-functionalist solution to the problem. He also presents a discussion of Thomas Reid's distinction between sensation and perception.Humphrey's main contention is that mental states are typically incorrectly described as objects of sensory experience rather than as affectively charged, mental representations similar to bodily activities. According to Humphrey, unless sensations can be thought of as physical-like objects that are an activity, (‘We do not have pains, we get to be pained,’ p. 13), one cannot get the ‘mind’ side of the mind–body problem to be of the same form as the brain side. Thus, in his account, sensation is conceptualized as being more like a mental representation of a ‘motor’ activity rather than as a sensory activity. Humphrey suggests that this can be seen as the result of evolutionary development in single-celled organisms. Initially these simple cells ‘wriggled redly’ when red light hit their cell surface. Later on, the animal not only detected what occurred at a sensory surface, but by monitoring its own reactions to stimuli, formed a representation of ‘what is happening to me’ (p. 16). At this point, the animal did not care about where the stimulation was coming from or what caused the stimulation but simply the ‘affect-laden, modality-specific, body-centred representation of what the stimulation is doing to me’ (p. 17). This is Thomas Reid's definition of sensation (p. 11). Reid's definition of perception is rather ‘what is happening out there?’ (p. 17) and ‘what is causing what is out there?’. Humphrey then describes five characteristics of sensation, with phenomenal immediacy (‘sensations are known directly and immediately; they do not need to be inferred’) being most important. Unlike perceptions, sensations are not interpreted.On the positive side of this issue, Rovane noted that ‘Humphrey's account of the position of qualia in mental life is the most promising and fertile that I have seen. I am especially impressed by his pivotal idea that sensation is itself a species of affect-laden intentional activity’ (p. 89). Dennett, Ellis and Newton also have many positive things to say about this approach.On the negative side, though, it is unclear why it would be adaptive to develop phenomenal experiences (e.g. ‘what is happening to me?’) given Humphrey's emphasis on evolutionary adaptivity. Another serious problem appears to be that Humphrey's (and Reid's) concepts of sensation and perception appear to be part of the same processing stage. In this view, ‘what is happening to me’ and ‘what is out there’ are both characteristics of perception, while sensation merely involves transduction of physical energy into a form that the brain can understand. Thus, one is not conscious of raw sensations because sensations are not interpreted and are not integrated. Sensations without integration and interpretation are like William James’ concept of ‘blooming, buzzing, confusion’ experienced by infants. According to this unitary view of ‘what is happening of me’ and ‘what is happening out there’ Humphrey's assumption of phenomenal immediacy is wrong. This must be so because, as de Quincy notes (p. 76), Humphrey proposes that sensations are immediate whereas perceptions are delayed as a result of integration processes.Let us consider this issue in more detail by examining hue perception. The phenome-nological experience of ‘redness’ is not immediate and typically involves perceptual integration – contrary to Humphrey's contention. For example, most real-world hues are integrated. For the experience of ‘red’, many wavelengths of light (not just 660 nm) are transduced because most light is not monochromatic. Indeed, most hues are processed as metameric colors: some retinal cones might be activated by 600 nm wavelengths, others by 720 nm wavelengths, and still others by 660 nm wavelengths. The visual system integrates all these wavelengths and an ‘average’ hue is experienced phenomenologically. This processing of metameric colors, which results in the same phenomenological experience as that of laboratory-produced, monochromatic colors, appears to be problematic for the phenomenal immediacy assumption. Again, it appears that both ‘what is happening to me’ and ‘what is happening out there’ involve considerable amounts of perceptual integration [see also Hardcastle's similar point on the perceptual integration of our phenomenal experience of hues (p. 52), and Van Gulick's example of the red soda can, (p. 96)].If the case of metameric colors (or other examples of sensory integration) does irreparable damage to Humphrey's concept of immediate sensations, how does this harm his overall argument? Eilan notes that ‘… if we are to get right the notion of consciousness of the environment, as opposed to the mere possession of information about it, then the notion of perception that we need is not, contra Humphrey, conceptually independent of the properties he assigns to sensation. And, once this is conceded, we lose any motivation for insisting that the representation of the body has a primary role to play in the emergence of consciousness’ (p. 34).It seems that Humphrey realizes that color vision presents potential problems for his theory because he discusses it in considerable detail in his terminal reply chapter. He provides evidence of neuro-psychological dissociations between ‘what is happening to me’ and ‘what is happening out there’ (see p. 101). It should be noticed, though, that color agnosia (when a person retains the phenomenal experience of ‘redness’ but is no longer able to name the color of an object) does not solve the problem of the lack of immediacy of the phenomenal experience of metameric hues. Humphrey notes that it typically takes longer to name the colors of objects in a scene than to experience colors in a scene. Having acknowledged this, however, it seems to me that Humphrey is simply describing the distinction between discrimination and detection. Discrimination latencies are usually longer than detection latencies (e.g. choice reaction time is much slower than simple reaction time).Finally, Humphrey attempts to use a developmental argument for the separation of sensation and perception. For example, children develop color preferences before they learn to label these preferences. Such developmental arguments do not appear to be persuasive because a child could know ‘what is out there’ even if the child did not have a language label to name the color of a ball (e.g. see Jean Mandler's imagery-based theory of thinking 2xHow to build a baby: II. Conceptual primitives. Mandler, J.M. Psychol. Rev. 1992; 99: 587–604Crossref | PubMedSee all References2).Consequently, although Humphrey's ‘efferent-activity-that-I-am-aware-of’ theory of consciousness and his resulting solution to the mind–body problem presents readers with a myriad of important issues in consciousness, the theory itself seems to fall short.