There is an argument whichshows conclusively that if qualia are causallyimpotent we could have no possible grounds forbelieving that they exist. But if, as this argumentshows, qualia are causally potent with respect to thedescriptions we give of them, it is tolerably certainthat they are causally potent in other morebiologically significant respects. The empiricalevidence, from studies of the effect of lesions of thestriate cortex shows that what is missing inthe absence of visual qualia is the ability tocategorize sensory inputs in the (...) visual modality. This would suggest that the function of privateexperience is to supply what Broadbent callsthe evidence on which the categorization ofproblematic sensory inputs are based. At the sametime analysis of the causal relation shows that whatdifferentiates a causal relation from an accidentalspatio-temporal conjunction is the existence ofreciprocally related dispositional properties of theentities involved which combine to make it true thatif one member of the conjunction, the cause, had notexisted, the other, the effect, would not haveexisted. The possibility that qualia might bedispositional properties of experiences which, as itwere, supply the invisible glue that sticks cause toeffect in this case is examined, but finallyrejected. (shrink)

The question of whether non-human animals are conscious is of fundamental importance. There are already good reasons to think that many are, based on evolutionary continuity and other considerations. However, the hypothesis is notoriously resistant to direct empirical test. Numerous studies have shown behaviour in animals analogous to consciously-produced human behaviour. Fewer probe whether the same mechanisms are in use. One promising line of evidence about consciousness in other animals derives from experiments on metamemory. A study by Hampton (Proc Natl (...) Acad Sci USA 98(9):5359–5362, 2001 ) suggests that at least one rhesus macaque can use metamemory to predict whether it would itself succeed on a delayed matching-to-sample task. Since it is not plausible that mere meta-representation requires consciousness, Hampton’s study invites an important question: what kind of metamemory is good evidence for consciousness? This paper argues that if it were found that an animal had a memory trace which allowed it to use information about a past perceptual stimulus to inform a range of different behaviours, that would indeed be good evidence that the animal was conscious. That functional characterisation can be tested by investigating whether successful performance on one metamemory task transfers to a range of new tasks. The paper goes on to argue that thinking about animal consciousness in this way helps in formulating a more precise functional characterisation of the mechanisms of conscious awareness. (shrink)

In three macaque monkeys with unilateral removal of primary visual cortex and in one unoperated monkey, we measured reaction times to a visual target that was presented at a lateral eccentricity of 20o in the normal, left, visual hemifield. When an additional stimulus was presented at the corresponding position in the right hemifield (hemianopic in three of the monkeys), it significantly slowed the reaction time to the left target if it preceded it by delays from 100-500 msec. The most effective (...) delay depended on the particular experimental paradigm and perhaps on the experience of the monkey with the task. The results show that reaction times to seen targets in the normal hemifield of monkeys are influenced by the presentation of ''unseen'' targets in the anopic hemifield, as in some patients with cortically blind visual field defects. (shrink)