Online research in philosophy

This paper sketches a phenomenological analysis of visual mental imagery and uses it to criticize representationalism and the internalist-versus-externalist framework for understanding consciousness. Contrary to internalist views of mental imagery imagery experience is not the experience of a phenomenal mental picture inspected by the mind’s eye, but rather the mental simulation of perceptual experience. Furthermore, there are experiential differences in perceiving and imagining that are not differences in the properties represented by these experiences. Therefore, externalist representationalism, which maintains that the properties of experience are the external properties represented by experience, is an inadequate account of conscious experience.

An introduction to the science and philosophy of mental imagery.

& The functional equivalence of overt movements and dynamic imagery is of fundamental importance in neuroscience. Here, we investigated the participation of the neocortical motor areas in a classic task of dynamic imagery, Shepard and Metzler's mental rotation task, by time-resolved single-trial functional Magnetic Resonance Imaging (fMRI). The subjects performed the mental-rotation task 16 times, each time with different object pairs. Functional images were acquired for each pair separately, and the onset times and..

One property of the emulator framework presented by Grush is that imagery operates off-line. Contrary to this viewpoint, we present evidence showing that mental rotation of a simple figure modulates low-level features of drawing articulation. This effect is dependent upon the type of rotation, suggesting a more integrative online role for imagery than proposed by the target article.

The emulation theory of representation is developed and explored as a framework that can revealingly synthesize a wide variety of representational functions of the brain. The framework is based on constructs from control theory (forward models) and signal processing (Kalman filters). The idea is that in addition to simply engaging with the body and environment, the brain constructs neural circuits that act as models of the body and environment. During overt sensorimotor engagement, these models are driven by efference copies in parallel with the body and environment, in order to provide expectations of the sensory feedback, and to enhance and process sensory information. These models can also be run off-line in order to produce imagery, estimate outcomes of different actions, and evaluate and develop motor plans. The framework is initially developed within the context of motor control, where it has been shown that inner models running in parallel with the body can reduce the effects of feedback delay problems. The same mechanisms can account for motor imagery as the off-line driving of the emulator via efference copies. The framework is extended to account for visual imagery as the off-line driving of an emulator of the motor-visual loop. I also show how such systems can provide for amodal spatial imagery. Perception, including visual perception, results from such models being used to form expectations of, and to interpret, sensory input. I close by briefly outlining other cognitive functions that might also be synthesized within this framework, including reasoning, theory of mind phenomena, and language. Key Words: efference copies; emulation theory of representation; forward models; Kalman filters; motor control; motor imagery; perception; visual imagery.

Mandik (2010) defends a motor theory of control consciousness according to which nonsensory states, like motor commands, directly contribute to the awareness we have of ourselves as being in control of our actions. Along the way, he argues that his theory is to be preferred over Prinz’s (2007) sensory imagery theory, which denies that nonsensory states play any direct role in the generation of control consciousness. I argue that Mandik’s criticisms of Prinz’s theory fall short, but that nonetheless there are reasons to favor a motor theory of control consciousness over a sensory imagery theory.

Inspired by Rick Grush's emulation theory, we reinterpreted a series of our neuroimaging experiments which were intended to examine the representations of complex movement, modality-specific imagery, and supramodal imagery. The emulation theory can explain motor and cognitive activities observed in cortical motor areas, through the speculation that caudal areas relate to motor-specific imagery and rostral areas embrace an emulator for amodal imagery.

In his article Grush proposes a potentially useful framework for explaining motor control, imagery, and perception. In our commentary we will address two issues that the model does not seem to deal with appropriately: one concerns motor control, and the other, the visual and motor imagery domains. We will consider these two aspects in turn.

Illusory kinesthetic sensation was influenced by motor imagery of the wrist following tendon vibration. The imagery and the illusion conditions commonly activated the contralateral cingulate motor area, supplementary motor area, dorsal premotor cortex, and ipsilateral cerebellum. This supports the notion that motor imagery is a mental rehearsal of movement, during which expected kinesthetic sensation is emulated by recruiting multiple motor areas, commonly activated by pure kinesthesia.

Pylyshyn provides sound arguments against the dominant picture theory of mental imagery. However, we claim that mental imagery is intrinsically dynamic and that the very nature of mental imagery will not be uncovered by studying static pictures. Understanding mental imagery of motor actions reveals that any theory of mental imagery should start off with the temporal nature of real-life experiences.