The hare and the snail: Dissociating visual orienting from conscious perception

A method for investigating attentional effects of peripheral visual objects, independently of perceptual identification, is described. We report an experiment using this method which shows that visual processing of peripheral objects differs radically, depending on whether participants move attention in response to an object or consciously perceive that object. When luminance contrast was reduced, conscious perceptual discrimination of peripheral letters was massively slower and less accurate—but both low and high contrast letters elicited rapid attentional orienting effects and these rapid orienting effects were equal in magnitude across low and high contrast. This pattern is consistent with known differences in luminance sensitivity between the dorsal and ventral visual processing streams, and with rapid dorsal–ventral interaction mediated via re-entrant feedback. Our findings show that the control system responsible for rapid movements of attention is exquisitely sensitive to visual form information at low levels of contrast, and involves a different neurocognitive pathway to that which gives rise to conscious perception.     

Costs and benefits of tool-use on the perception of reachable space

Previous studies have shown that using a tool modifies in a short time-scale both near-body space perception and arm-length representation in the body schema. However, to date no research has specifically investigated the effect of tool-use on an action-related perceptual task. We report here a study assessing the effect of tool-use on the perception of reachable space for perceptual estimates made in reference to either the tool or the hand. Using the tool on distal objects resulted in an extension of perceived reachable space with the tool and reduced the variability of reachability estimates. Tool use also extended perceived reachable space with the hand, but with a concomitant increase of the variability of reachability estimates. These findings suggest that tool incorporation into the represented arm following tool-use improves the anticipation of action possibilities with the tool, while hand representation becomes less accurate.     

Image statistics and the perception of apparent motion

The short- and long-range apparent motion processes are discussed in terms of the statistical properties of images. It is argued that the short-range process, exemplified by the random-dot kinematogram, is primarily sensitive to the dipole statistics, whereas the long-range process, exemplified by illusory occlusion, is treated by the visual system primarily in terms of the tripole and higher statistical correlation functions. The studies incorporate the balanced dot, which is a unique stimulus element that permits high pass filtering while preserving detailed positional information. Low spatial frequencies are shown to be critical for texture segregation in random-dot kinematograms, independent of the grain size or number density of texture elements. Illusory path perception in the long-range process is shown not to require low spatial frequencies, but is sensitive rather to global temporal phase coherency. These results are interpreted in terms of the respective roles of the power and phase spectra in perceptual organization. The construction of balanced dots is discussed in detail.     

When believing is seeing: The role of predictions in shaping visual perception

The study investigated the influence of predictions on perception—in particular, how strong but erroneous prediction coupled with poor sensory data can trigger misperceptions. Using signal detection, we tested whether predictions induced by a semantic cue change the recognition threshold (criterion) or the subjectively perceived differences between stimuli (sensitivity). In a series of 3 experiments, participants observed pictures of (a) real objects distorted to various extents (targets), (b) noise with elements corresponding to meaningful objects (foils), or (c) nonsense images (noise). Stimuli were preceded either by a semantic cue or by a blank screen with equal probability. Presence of the cue resulted in a more liberal criterion, but only for targets and foils. The cue decreased sensitivity between the distorted targets, but increased sensitivity between the targets and noise—that is, the cue increased between-class differences, but decreased within-class differences. When there was no correspondence between prediction and the sensory input, prediction actually increased the chances of correctly rejecting noise. The influence of the cue was strongest for the moderately distorted targets and foils—when uncertainty related to the bottom-up input was the highest.     

Facilitation effect of observed motor deviants in a cooperative motor task: Evidence for direct perception of social intention in action

Spatiotemporal parameters of voluntary motor action may help optimize human social interactions. Yet it is unknown whether individuals performing a cooperative task spontaneously perceive subtly informative social cues emerging through voluntary actions. In the present study, an auditory cue was provided through headphones to an actor and a partner who faced each other. Depending on the pitch of the auditory cue, either the actor or the partner were required to grasp and move a wooden dowel under time constraints from a central to a lateral position. Before this main action, the actor performed a preparatory action under no time constraint, consisting in placing the wooden dowel on the central location when receiving either a neutral (“prêt”–ready) or an informative auditory cue relative to who will be asked to perform the main action (the actor: “moi”–me, or the partner: “lui”–him). Although the task focused on the main action, analysis of motor performances revealed that actors performed the preparatory action with longer reaction times and higher trajectories when informed that the partner would be performing the main action. In this same condition, partners executed the main actions with shorter reaction times and lower velocities, despite having received no previous informative cues. These results demonstrate that the mere observation of socially driven motor actions spontaneously influences the low-level kinematics of voluntary motor actions performed by the observer during a cooperative motor task. These findings indicate that social intention can be anticipated from the mere observation of action patterns.     

Counterexample to the hypothesis of functional similarity between tactile and visual pattern perception

In earlier work, the author has demonstrated that tactile pattern perception and visual pattern perception exhibit many parallels when the effective spatial resolution of vision is reduced to that of touch, thus supporting the hypothesis that the two pattern senses are functionally similar when matched in spatial bandwidth. The present experiments demonstrate a clear counter-example to this hypothesis of functional similarity. Specifically, it was found that the lateral masking effect of a surround on tactile character recognition increases when the surround changes in composition from solid lines to dots, whereas for vision, recognition performance goes in the opposite direction. This finding necessitates some modification of the model of character recognition proposed by the author (Loornis, 1990) as it applies to the sensing of raised tactile patterns. One possible modification would be to incorporate, as the initial stage of pattern transformation, the continuum mechanics model for the skin that was developed by Phillips and Johnson (1981b).     

Length distortion of temporally extended visual displays: similarity to haptic spatial perception

Three experiments were designed to investigate length distortion--the tendency to inflate estimates of the inferred distance between two points, as the length of a circuitous pathway between them increases. This phenomenon, previously demonstrated with haptic and locomotor exploration (Lederman, Klatzky, Collins, & Wardell, 1987), was extended to vision through the presentation of pathways as a temporal sequence of illuminated points. The magnitude of the visual effect was less than that previously found in haptics, and conditions promoting the effect included a relatively slow presentation rate and moderately complex pathways. Commonalities in the pattern, if not the magnitude, of length distortion in vision and haptics suggest that similar processes of spatial encoding may underlie the phenomenon in both domains.     

Across space and time: infants learn from backward and forward visual statistics

This study investigates whether infants are sensitive to backward and forward transitional probabilities within temporal and spatial visual streams. Two groups of 8‐month‐old infants were familiarized with an artificial grammar of shapes, comprising backward and forward base pairs (i.e. two shapes linked by strong backward or forward transitional probability) and part‐pairs (i.e. two shapes with weak transitional probabilities in both directions). One group viewed the continuous visual stream as a temporal sequence, while the other group viewed the same stream as a spatial array. Following familiarization, infants looked longer at test trials containing part‐pairs than base pairs, although they had appeared with equal frequency during familiarization. This pattern of looking time was evident for both forward and backward pairs, in both the temporal and spatial conditions. Further, differences in looking time to part‐pairs that were consistent or inconsistent with the predictive direction of the base pairs (forward or backward) indicated that infants were indeed sensitive to direction when presented with temporal sequences, but not when presented with spatial arrays. These results suggest that visual statistical learning is flexible in infancy and depends on the nature of visual input.     

Mapping the color space of saccadic selectivity in visual search

Color coding is used to guide attention in computer displays for such critical tasks as baggage screening or air traffic control. It has been shown that a display object attracts more attention if its color is more similar to the color for which one is searching. However, what does similar precisely mean? Can we predict the amount of attention that a display color will receive during a search for a given target color? To tackle this question, two color‐search experiments measuring the selectivity of saccadic eye movements and mapping out its underlying color space were conducted. A variety of mathematical models, predicting saccadic selectivity for given target and display colors, were devised and evaluated. The results suggest that applying a Gaussian function to a weighted Euclidean distance in a slightly modified HSI color space is the best predictor of saccadic selectivity in the chosen paradigm. Hue and intensity information by itself provides a basis for useful predictors, spanning a possibly spherical color space of saccadic selectivity. Although the current models cannot predict saccadic selectivity values for a wide variety of visual search tasks, they reveal some characteristics of color search that are of both theoretical and applied interest, such as for the design of human–computer interfaces.     

Near-hand effects are robust: Three OSF pre-registered replications of visual biases in perihand space

ABSTRACT

Although previous work provides evidence that observers experience biases in visual processing when they view stimuli in perihand space, a few recent investigations have questioned the reliability of these near-hand effects. We addressed this controversy by running three pre-registered replication experiments. Experiment 1 was a replication of one of the initial studies on facilitated target detection near the hands in which participants performed an attentional cueing task while placing a single hand either near or far from the display. Experiment 2 tested the same paradigm while adopting the design of a recent experiment that called into question near-hand facilitation. Experiment 3 was a replication of a study in which hand proximity influenced working memory performance in a change detection paradigm. Across all three experiments, we found significant interactions between hand position and stimulus characteristics that indicated the hands’ presence altered visual processing, bolstering evidence favouring the robustness of near-hand effects.     

Varieties of cognitive penetration in visual perception

Is our perceptual experience a veridical representation of the world or is it a product of our beliefs and past experiences? Cognitive penetration describes the influence of higher level cognitive factors on perceptual experience and has been a debated topic in philosophy of mind and cognitive science. Here, we focus on visual perception, particularly early vision, and how it is affected by contextual expectations and memorized cognitive contents. We argue for cognitive penetration based on recent empirical evidence demonstrating contextual and top-down influences on early visual processes. On the basis of a perceptual model, we propose different types of cognitive penetration depending on the processing level on which the penetration happens and depending on where the penetrating influence comes from. Our proposal has two consequences: (1) the traditional controversy on whether cognitive penetration occurs or not is ill posed, and (2) a clear-cut perception–cognition boundary cannot be maintained.     

Relating the perception of visual ensemble statistics to individual levels of autistic traits

Integrating information across the visual field into an ensemble (e.g., seeing the forest from the trees) is an effective strategy to efficiently process the visual world, and one that is often impaired in autism spectrum disorder. Individual differences in sensory processing predict ensemble encoding, providing a potential mechanism for differing perceptual strategies across individuals, and possibly across diagnostic groups exhibiting atypical sensory processing. Here, we explore whether ensemble encoding is associated with traits associated with autism spectrum disorder (ASD). Participants (N=68) were presented with an ensemble display consisting of circles of varying sizes and colors, and were asked to remember the size of the red and blue circles, while ignoring the green circles. Participants were then cued to a target location after a brief delay, and instructed to report the remembered size of the circle they had previously viewed in that location, as ensemble information commonly biases memory for individual objects toward the probed mean of a set of similar objects. The Autism-spectrum Quotient (AQ) was completed to measure each individual’s level of autistic traits. We found that an individual’s level of ensemble perception, measured as their bias toward the probed mean, was negatively associated with a higher level of ASD traits. These results suggest that individuals with higher levels of ASD traits are less likely to integrate perceptual information. These findings may shed light on different perceptual processing within the autism spectrum, and provide insight into the relationship between individual differences and ensemble encoding.     

Kinetic potential influences visual and remote haptic perception of affordances for standing on an inclined surface

The ability of a perceiver–actor to perform a particular behaviour depends on their ability to generate and control the muscular forces required to perform that behaviour. If an intended behaviour is to be successful, perception must be relative to this ability. We investigated whether perceiver–actors were sensitive to how changes in their mass distribution influenced their ability to stand on an inclined surface. Participants reported whether they would be able to stand on an inclined surface while wearing a weighted backpack on their back, while wearing a weighted backpack on their front, and while not wearing a weighted backpack. In addition, participants performed this task by either viewing the surface or exploring it with a hand-held rod (while blindfolded). The results showed that perception of affordances for standing on the inclined surface depended on how the backpack influenced the ability of the participant to stand on the surface. Specifically, perceptual boundaries occurred at steeper inclinations when participants wore the backpack on their front than when they wore it on their back. Moreover, this pattern occurred regardless of the perceptual modality by which the participants explored the inclined surface.     

Relational invariance and visual space perception: On perceptual vector analysis of the optic flow

The outlines of the theory of perceptual vector analysis in visual space and motion perception in its present state of development are presented. This theory is exclusively founded on the outcome of systematic experimental research extended over more than three decades. Some informative experiments and their results are briefly described, starting with some decisive findings reported in Johansson (1950). A fundamental difference between this approach and the traditional pictorial way of describing the proximal stimulus is that it accepts abstract mathematical relations in spatial change over time in the optic flow hitting the receptor organs as specification of the proximal stimulus rather than the traditional interpretation of cues in static images. In its present form it is able to establish functionally valid mathematical correspondence between the light-reflecting environment, geometrical transformations in the optic flow at the retina and the percept.     

On the distinction between perception and cognition

To uphold the distinction between perception and cognition for certain classes of tasks or phenomena, it is proposed that three criteria must be met: (1) when perceptual and cognitive functions serve different biological purposes, (2) when stimulus information in dynamic events is necessary, but not sufficient for veridical perception, and (3) when the task emphasizes explicit retrieval, as opposed to implicit use of information. Conversely, when the three criteria have not been met, conditions for theoretical unification exist.     

Seeing and believing: perception,belief formation and the divided mind

On many of the idealized models of human cognition and behavior in use by philosophers, agents are represented as having a single corpus of beliefs which (a) is consistent and deductively closed, and (b) guides all of their (rational, deliberate, intentional) actions all the time. In graded-belief frameworks, agents are represented as having a single, coherent distribution of credences, which guides all of their (rational, deliberate, intentional) actions all of the time. It’s clear that actual human beings don’t live up to this idealization. The systems of belief that we in fact have are fragmented. Rather than having a single system of beliefs that guides all of our behavior all of the time, we have a number of distinct, compartmentalized systems of belief, different ones of which drive different aspects of our behavior in different contexts. It’s tempting to think that, while of course people are fragmented, it would be better (from the perspective of rationality) if they weren’t, and the only reason why our fragmentation is excusable is that we have limited cognitive resources, which prevents us from holding too much information before our minds at a time. Give us enough additional processing capacity, and there’d be no justification for any continued fragmentation. I argue that this is not so. There are good reasons to be fragmented rather than unified, independent of the limitations on our available processing power. In particular, there are ways our belief-forming mechanisms—including our perceptual systems—could be constructed that would make it better to be fragmented than to be unified. And there are reasons to think that some of our belief-forming mechanisms really are constructed that way.

Viewing artworks: Contributions of cognitive control and perceptual facilitation to aesthetic experience

When we view visual images in everyday life, our perception is oriented toward object identification. In contrast, when viewing visual images as artworks, we also tend to experience subjective reactions to their stylistic and structural properties. This experiment sought to determine how cognitive control and perceptual facilitation contribute to aesthetic perception along with the experience of emotion. Using functional MRI, we show that aesthetic perception activated bilateral insula which we attribute to the experience of emotion. Moreover, while adopting the aesthetic orientation activated the left lateral prefrontal cortex, paintings that facilitated visuospatial exploration activated the left superior parietal lobule. The results suggest that aesthetic experience is a function of the interaction between top-down orienting of attention and bottom-up perceptual facilitation.     

Body ownership affects visual perception of object size by rescaling the visual representation of external space

Size perception is most often explained by a combination of cues derived from the visual system. However, this traditional cue approach neglects the role of the observer’s body beyond mere visual comparison. In a previous study, we used a full-body illusion to show that objects appear larger and farther away when participants experience a small artificial body as their own and that objects appear smaller and closer when they assume ownership of a large artificial body (“Barbie-doll illusion”; van der Hoort, Guterstam, & Ehrsson, PLoS ONE, 6(5), e20195, 2011). The first aim of the present study was to test the hypothesis that this own-body-size effect is distinct from the role of the seen body as a direct familiar-size cue. To this end, we developed a novel setup that allowed for occlusion of the artificial body during the presentation of test objects. Our results demonstrate that the feeling of ownership of an artificial body can alter the perceived sizes of objects without the need for a visible body. Second, we demonstrate that fixation shifts do not contribute to the own-body-size effect. Third, we show that the effect exists in both peri-personal space and distant extra-personal space. Finally, through a meta-analysis, we demonstrate that the own-body-size effect is independent of and adds to the classical visual familiar-size cue effect. Our results suggest that, by changing body size, the entire spatial layout rescales and new objects are now perceived according to this rescaling, without the need to see the body.