The Stroop effect and mental imagery.

The classic Stroop task is very simple: you have to name the color of words printed on a page. If these words are color words (like "red" or "blue"), where the color named and the color it is printed in are different (say, "red" printed in blue), the reaction time increases significantly. My aim is to argue that the existing psychological explanations of the Stroop effect need to be supplemented. The Stroop effect is not exclusively about access to motor control. It is also, to a large extent, about interferences in perceptual processing. To put it briefly, reading the color word triggers-laterally and automatically-visual imagery of the color and this interferes with the processing of the perceived color of the word. In other words, the Stroop effect is to a large extent a sensory phenomenon, and it has less to do with attention, conflict monitoring, or other higher-level phenomena.

Amodal completion and relationalism.

Amodal completion is usually characterized as the representation of those parts of the perceived object that we get no sensory stimulation from. In the case of the visual sense modality, for example, amodal completion is the representation of occluded parts of objects we see. I argue that relationalism about perception, the view that perceptual experience is constituted by the relation to the perceived object, cannot give a coherent account of amodal completion. The relationalist has two options: construe the perceptual relation as the relation to the entire perceived object or as the relation to the unoccluded parts of the perceived object. I argue that neither of these options are viable.

What do we see in pictures? The sensory individuals of picture perception.

When I am looking at an apple, I perceptually attribute certain properties to certain entities. Two questions arise: what are these entities (what is it that I perceptually represent as having properties) and what are these properties (what properties I perceive this entity as having)? This paper is about the former, less widely explored, question: what does our perceptual system attribute properties to? In other words, what are these 'sensory individuals'. There have been important debates in philosophy of perception about what sensory individuals would be the most plausible candidates for which sense modalities. The aim of this paper is to ask a related question about picture perception: what is the sensory individual of picture perception? When we look at a picture and see an apple depicted in it, what kind of entity do we see? What do we perceptually attribute properties to? I argue that the most straightforward candidates (ordinary objects, sui generis sensory individuals, no sensory individuals) are all problematic and that the most plausible candidate for the sensory individuals of picture perception are spatiotemporal regions.

Perception is not all-purpose.

I aim to show that perception depends counterfactually on the action we want to perform. Perception is not all-purpose: what we want to do does influence what we see. After clarifying how this claim is different from the one at stake in the cognitive penetrability debate and what counterfactual dependence means in my claim, I will give a two-step argument: (a) one's perceptual attention depends counterfactually on one's intention to perform an action (everything else being equal) and (b) one's perceptual processing depends counterfactually on one's perceptual attention (everything else being equal). If we put these claims together, what we get is that one's perceptual processing depends counterfactually on one's intention to perform an action (everything else being equal).

Imagining one experience to be another.

I can imagine a banana to be a phone receiver. I can also imagine the flapping of my arms to be flying. So it is possible to imagine one thing to be another-at least for some types of 'things'. I will argue that although it is possible to imagine an object to be another object and it is also possible to imagine an activity to be a different activity, one cannot imagine one's present sensory experience to be a different sensory experience with different qualitative character. This claim will have some important consequences beyond the philosophy of imagination, for example, for some accounts of depiction.

Threefoldness.

Theories of picture perception aim to understand our perceptual relation to both the picture surface and the depicted object. I argue that we should talk about not two, but three entities when understanding picture perception: (A) the picture surface, (B) the three dimensional object the picture surface visually encodes and (C) the three dimensional depicted object. As (B) and (C) can come apart, we get a more complex picture of picture perception than normally assumed and one where the notion of twofoldness, which has played an important albeit controversial role in understanding picture perception is replaced by the concept of threefoldness.

How to (and how not to) think about top-down influences on visual perception.

The question of whether cognition can influence perception has a long history in neuroscience and philosophy. Here, we outline a novel approach to this issue, arguing that it should be viewed within the framework of top-down information-processing. This approach leads to a reversal of the standard explanatory order of the cognitive penetration debate: we suggest studying top-down processing at various levels without preconceptions of perception or cognition. Once a clear picture has emerged about which processes have influences on those at lower levels, we can re-address the extent to which they should be considered perceptual or cognitive. Using top-down processing within the visual system as a model for higher-level influences, we argue that the current evidence indicates clear constraints on top-down influences at all stages of information processing; it does, however, not support the notion of a boundary between specific types of information-processing as proposed by the cognitive impenetrability hypothesis.

Sensory Substitution and Multimodal Mental Imagery.

Many philosophers use findings about sensory substitution devices in the grand debate about how we should individuate the senses. The big question is this: Is "vision" assisted by (tactile) sensory substitution really vision? Or is it tactile perception? Or some sui generis novel form of perception? My claim is that sensory substitution assisted "vision" is neither vision nor tactile perception, because it is not perception at all. It is mental imagery: visual mental imagery triggered by tactile sensory stimulation. But it is a special form of mental imagery that is triggered by corresponding sensory stimulation in a different sense modality, which I call "multimodal mental imagery."

Unconscious goals: specific or unspecific? The potential harm of the goal/gene analogy.

Huang & Bargh's (H&B's) definition of goals is ambiguous between "specific goals" - the end-state of a token action I am about to perform - and "unspecific goals" - the end-state of an action-type (without specifying how this would be achieved). The analogy with selfish genes pushes the authors towards the former interpretation, but the latter would provide a more robust theoretical framework.

Unconscious mental imagery.

Historically, mental imagery has been defined as an experiential state-as something necessarily conscious. But most behavioural or neuroimaging experiments on mental imagery-including the most famous ones-do not actually take the conscious experience of the subject into consideration. Further, recent research highlights that there are very few behavioural or neural differences between conscious and unconscious mental imagery. I argue that treating mental imagery as not necessarily conscious (as potentially unconscious) would bring much needed explanatory unification to mental imagery research. It would also help us to reassess some of the recent aphantasia findings inasmuch as at least some subjects with aphantasia would be best described as having unconscious mental imagery. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Offline perception: an introduction.

Experiences that are self-generated and independent of sensory stimulations permeate our whole life. This theme issue examines their similarities and differences, systematizes the literature from an integrative perspective, critically discusses state-of-the-art empirical findings and proposes new theoretical approaches. The aim of the theme issue is to foster interaction between the different disciplines and research directions involved and to explore the prospects of a unificatory account of offline perception in general. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Synesthesia as (Multimodal) Mental Imagery.

It has been repeatedly suggested that synesthesia is intricately connected with unusual ways of exercising one's mental imagery, although it is not always entirely clear what the exact connection is. My aim is to show that all forms of synesthesia are forms of (often very different kinds of) mental imagery and, further, if we consider synesthesia to be a form of mental imagery, we get significant explanatory benefits, especially concerning less central cases of synesthesia where the inducer is not sensory stimulation.

Vicarious representation: A new theory of social cognition.

Theory of mind, the attribution of mental states to others is one form of social cognition. The aim of this paper is to highlight the importance of another, much simpler, form of social cognition, which I call vicarious representation. Vicarious representation is the attribution of other-centered properties to objects. This mental capacity is different from, and much simpler than, theory of mind as it does not imply the understanding (or representation) of the mental (or even perceptual) states of another agents. I argue that the most convincing experiments that are supposed to show that non-human primates have theory of mind in fact demonstrate that they are capable of vicarious representation. The same is true for the experiments about the theory of mind of infants under 12 months.

The Importance of Amodal Completion in Everyday Perception.

Amodal completion is the representation of those parts of the perceived object that we get no sensory stimulation from. In the case of vision, it is the representation of occluded parts of objects we see: When we see a cat behind a picket fence, our perceptual system represents those parts of the cat that are occluded by the picket fence. The aim of this piece is to argue that amodal completion plays a constitutive role in our everyday perception and trace the theoretical consequences of this claim.

Multimodal mental imagery.

When I am looking at my coffee machine that makes funny noises, this is an instance of multisensory perception - I perceive this event by means of both vision and audition. But very often we only receive sensory stimulation from a multisensory event by means of one sense modality, for example, when I hear the noisy coffee machine in the next room, that is, without seeing it. The aim of this paper is to bring together empirical findings about multimodal perception and empirical findings about (visual, auditory, tactile) mental imagery and argue that on occasions like this, we have multimodal mental imagery: perceptual processing in one sense modality (here: vision) that is triggered by sensory stimulation in another sense modality (here: audition). Multimodal mental imagery is not a rare and obscure phenomenon. The vast majority of what we perceive are multisensory events: events that can be perceived in more than one sense modality - like the noisy coffee machine. And most of the time we are only acquainted with these multisensory events via a subset of the sense modalities involved - all the other aspects of these multisensory events are represented by means of multisensory mental imagery. This means that multisensory mental imagery is a crucial element of almost all instances of everyday perception.

Natural selection and the limitations of environmental resources.

In this paper, I am clarifying and defending my argument (Nanay 2005) in favor of the claim that cumulative selection can explain adaptation provided that the environmental resources are limited. Further, elaborate on what this limitation of environmental resources means and why it is relevant for the explanatory power of natural selection.