Was sollen wir tun? Was dürfen wir glauben? - bei DuEPublico ...

270 WEBER & VOSGERAU
clear idea of how small adjustments of movement trajectories are made in actions, “online”-
controlling or -correction is somewhat less intelligible for thoughts and thus seems unlikely as
a common feature (cf. Vosgerau and Synofzik 2010). Movements can be run “offline” in
imagination—a feature that is hardly to be found in thinking; it would consist in imagining a
thought without thinking it.
(iv) If the distinction between motor control and action cognition is denied, there would be no
sense in talking about “grounded” cognition at all, since then there is nothing left to be
“grounded”. This means that the truth of the strong thesis would preclude the formulation of
any claim about grounded action cognition and is thus to be abandoned as a sensible version
of a grounded cognition thesis.
Thus, thoughts and motor processes are clearly distinguishable in important aspects and the
strong thesis can already be rejected on conceptual reasons. Therefore, thoughts cannot be a
kind of motor ability.
Now, we want to take a closer look on the empirical evidence that can decide between the two
suggested more plausible versions of grounded action cognition. Several studies suggest that
impaired motor control mechanisms influence action cognition, such that action cognition is
degraded but not lost altogether. Consider for instance, that deficits in word-description
matching associated with judgments about actions, but not judgments about objects,
correlate with cortical atrophy in motor regions, such as amyotrophic lateral sclerosis (ALS)
(cf. Grossman et al. 2008). This suggests that degraded (although not completely absent)
knowledge of action features—an obvious case for a process of action cognition—is due to
impairments of the motor cortex of those patients. If this is correct, then ALS is not only a
neurodegenerative condition affecting the motor system, but also a cognitive impairment of
the comprehension of action related words. Similarly, Parkinson’s disease patients present a
significant impairment, without complete loss, in their capacity to name actions (again, as
compared to their capacity to name objects). Moreover, these results support the idea that
verb representations are grounded in neural networks to which brain areas involved in motor
control contribute (cf. Rodríguez-Ferreiro et al. 2009). The fact that motor features
contribute to linguistic concept application and comprehension is evidence for the moderate
thesis (2) and evidence against the weak thesis (3): motor abilities are constitutive of
processes within the domain of action cognition.
Diseases of the brain’s motor systems, e.g. of the cerebellum (cerebellar ataxia) or the basal
ganglia (Parkinson’s disease), have traditionally been considered to be solely “motor
disorders”. But as seen above, behavioral experiments with patients suffering from these
disorders show that motor deficits are accompanied by action perception and action cognition
deficits. Other studies demonstrate that not only motor, but also perceptual abilities are basic
for action cognition (cf. Adamovich et al. 2001; Konczak et al. 2009; Maschke et al. 2003).
Some motor deficits are actually secondary to action perception deficits, like shortcomings in
the perception of one’s own actions. For instance, it seems that patients with cerebellar
lesions are impaired in motor control because they lack updated internal sensory predictions
of the visual consequences of their motor behavior: thus, the patients’ impairments in motor
control are due to an impaired perception of their own actions and not the other way round
(cf. Synofzik, Lindner and Their 2008). This suggests that action perception dysfunctions do
not just accompany motor dysfunctions, but rather motor deficits seem to go—surprisingly—
hand in hand with selective deficits in action perception and action cognition. Are these
genuinely “motor deficits”, or are they deficits in action perception, or even deficits in action
cognition? The lack of clear answers here suggests that “motor disorders” are not just motor
disorders. Overall, the fact that the boundaries between these different domains become
blurry is consistent with (2) and is a counterexample to (3).
We now want to focus on the influence of motor factors and thoughts on perceiving one’s own
and other’s agency. For example, misattributions of agency of one’s actions in schizophrenia