Prior Visual Experience Research Articles

Angular declination and the dynamic perception of egocentric distance.

The extraction of the distance between an object and an observer is fast when angular declination is informative, as it is with targets placed on the ground. To what extent does angular declination drive performance when viewing time is limited? Participants judged target distances in a real-world environment with viewing durations ranging from 36-220 ms. An important role for angular declination was supported by experiments showing that the cue provides information about egocentric distance even on the very first glimpse, and that it supports a sensitive response to distance in the absence of other useful cues. Performance was better at 220-ms viewing durations than for briefer glimpses, suggesting that the perception of distance is dynamic even within the time frame of a typical eye fixation. Critically, performance in limited viewing trials was better when preceded by a 15-s preview of the room without a designated target. The results indicate that the perception of distance is powerfully shaped by memory from prior visual experience with the scene. A theoretical framework for the dynamic perception of distance is presented.

How Does Experience Modulate Auditory Spatial Processing in Individuals with Blindness?

Comparing early- and late-onset blindness in individuals offers a unique model for studying the influence of visual experience on neural processing. This study investigated how prior visual experience would modulate auditory spatial processing among blind individuals. BOLD responses of early- and late-onset blind participants were captured while performing a sound localization task. The task required participants to listen to novel “Bat-ears” sounds, analyze the spatial information embedded in the sounds, and specify out of 15 locations where the sound would have been emitted. In addition to sound localization, participants were assessed on visuospatial working memory and general intellectual abilities. The results revealed common increases in BOLD responses in the middle occipital gyrus, superior frontal gyrus, precuneus, and precentral gyrus during sound localization for both groups. Between-group dissociations, however, were found in the right middle occipital gyrus and left superior frontal gyrus. The BOLD responses in the left superior frontal gyrus were significantly correlated with accuracy on sound localization and visuospatial working memory abilities among the late-onset blind participants. In contrast, the accuracy on sound localization only correlated with BOLD responses in the right middle occipital gyrus among the early-onset counterpart. The findings support the notion that early-onset blind individuals rely more on the occipital areas as a result of cross-modal plasticity for auditory spatial processing, while late-onset blind individuals rely more on the prefrontal areas which subserve visuospatial working memory.

Visually guided grasping of common objects: Effects of priming

Priming effects were tested on the planning of the grasping of common objects under full vision during action performance. Healthy participants took part in four experiments which manipulated the nature of the prime (objects, circular block, rectangular bar) and priming context (blocked vs. mixed). Each experiment relied on four priming conditions: (1) congruent orientation, (2) incongruent orientation, (3) neutral prime, and (4) no prime. Priming was observed to have a facilitating effect on visually guided grasping when the object to be grasped was primed by a congruently oriented identical object. This effect was rather independent of the priming context (experimental set-up). Our data suggest an object's functional identity may contribute to the priming effect, as well as its intrinsic (e.g., shape, size) and extrinsic (orientation) visual characteristics. We showed that the planning of visually guided grasping is influenced by prior visual experience, and thus that grasping is not based exclusively on real-time processing of visual information.

The cradle of causal reasoning: newborns’ preference for physical causality

Perception of mechanical (i.e. physical) causality, in terms of a cause-effect relationship between two motion events, appears to be a powerful mechanism in our daily experience. In spite of a growing interest in the earliest causal representations, the role of experience in the origin of this sensitivity is still a matter of dispute. Here, we asked the question about the innate origin of causal perception, never tested before at birth. Three experiments were carried out to investigate sensitivity at birth to some visual spatiotemporal cues present in a launching event. Newborn babies, only a few hours old, showed that they significantly preferred a physical causality event (i.e. Michotte's Launching effect) when matched to a delay event (i.e. a delayed launching; Experiment 1) or to a non-causal event completely identical to the causal one except for the order of the displacements of the two objects involved which was swapped temporally (Experiment 3). This preference for the launching event, moreover, also depended on the continuity of the trajectory between the objects involved in the event (Experiment 2). These results support the hypothesis that the human system possesses an early available, possibly innate basic mechanism to compute causality, such a mechanism being sensitive to the additive effect of certain well-defined spatiotemporal cues present in the causal event independently of any prior visual experience.

Bumblebee visual search for multiple learned target types

Visual search is well studied in human psychology, but we know comparatively little about similar capacities in non-human animals. It is sometimes assumed that animal visual search is restricted to a single target at a time. In bees, for example, this limitation has been evoked to explain flower constancy, the tendency of bees to specialise on a single flower type. Few studies, however, have investigated bee visual search for multiple target types after extended learning and controlling for prior visual experience. We trained colour-naive bumblebees (Bombus terrestris) extensively in separate discrimination tasks to recognise two rewarding colours in interspersed block training sessions. We then tested them with the two colours simultaneously in the presence of distracting colours to examine whether and how quickly they were able to switch between the target colours. We found that bees switched between visual targets quickly and often. The median time taken to switch between targets was shorter than known estimates of how long traces last in bees' working memory, suggesting that their capacity to recall more than one learned target was not restricted by working memory limitations. Following our results, we propose a model of memory and learning that integrates our findings with those of previous studies investigating flower constancy.

The effect of vertical and horizontal symmetry on memory for tactile patterns in late blind individuals

Visual stimuli that exhibit vertical symmetry are easier to remember than stimuli symmetric along other axes, an advantage that extends to the haptic modality as well. Critically, the vertical symmetry memory advantage has not been found in early blind individuals, despite their overall superior memory, as compared with sighted individuals, and the presence of an overall advantage for identifying symmetric over asymmetric patterns. The absence of the vertical axis memory advantage in the early blind may depend on their total lack of visual experience or on the effect of prolonged visual deprivation. To disentangle this issue, in this study, we measured the ability of late blind individuals to remember tactile spatial patterns that were either vertically or horizontally symmetric or asymmetric. Late blind participants showed better memory performance for symmetric patterns. An additional advantage for the vertical axis of symmetry over the horizontal one was reported, but only for patterns presented in the frontal plane. In the horizontal plane, no difference was observed between vertical and horizontal symmetric patterns, due to the latter being recalled particularly well. These results are discussed in terms of the influence of the spatial reference frame adopted during exploration. Overall, our data suggest that prior visual experience is sufficient to drive the vertical symmetry memory advantage, at least when an external reference frame based on geocentric cues (i.e., gravity) is adopted.

Incidental picture exposure affects later reading: Evidence from the N400

Language comprehenders form a mental representation of the implied shape of objects mentioned in the text. In the present study, the influence of prior visual experience on subsequent reading was assessed. In two separate phases, participants saw a picture of an object and read a text about the object, suggesting the same or a different shape. When the shapes in the two phases mismatched, ERPs during reading showed a larger N400 amplitude than when the shapes matched, suggesting that a picture presented incidentally 15min earlier affected reading. These results further strengthen the case for the interaction of language and visual experience during language comprehension.

Scalar reference, contrast and discourse: Separating effects of linguistic discourse from availability of the referent

Listeners expect that a definite noun phrase with a pre-nominal scalar adjective (e.g., the big …) will refer to an entity that is part of a set of objects contrasting on the scalar dimension, e.g., size ( Sedivy, Tanenhaus, Chambers, & Carlson, 1999). Two visual world experiments demonstrate that uttering a referring expression with a scalar adjective makes all members of the relevant contrast set more salient in the discourse model, facilitating subsequent reference to other members of that contrast set. Moreover, this discourse effect is caused primarily by linguistic mention of a scalar adjective and not by the listener’s prior visual or perceptual experience. These experiments demonstrate that language processing is sensitive to which information was introduced by linguistic mention, and that the visual world paradigm can be use to tease apart the separate contributions of visual and linguistic information to reference resolution.

Prior visual experience, and perception and memory of shape in people with total blindness

The aim of this study was to explore the role of prior visual experience for tactile differentiation of object shapes. The study investigated whether people who lost their vision later in life were able to identify and recognize object shapes more accurately and faster than those who were blind from their birth. Four experiments were conducted. The first two were concerned with tactile shape differentiation, the second two with shape recognition. The hypotheses were only partially confirmed. The ‘late’ blind participants distinguished shapes more accurately than the congenitally blind (particularly in ‘simple’ perception tasks). This finding may suggest that people who have prior visual experience use an allocentric strategy when visualizing object shapes in their imagery. The ‘late’ blind participants performed the tasks more slowly than those who were congenitally blind. This may be explained by the complexity of the task, the time needed to create an allocentric representation, and discrepancy in the tactile experiences between the congenitally and late blind groups. A number of implications for further research are outlined.

Rapid Communication: Readers Routinely Represent Implied Object Rotation: The Role of Visual Experience

We conducted an eye tracking experiment to investigate whether prior visual experience affects later language processing. We assessed the effects of previously encountered pictures of objects with a vertical or horizontal orientation on the later reading of sentences that implied an object's orientation. First-pass reading times were longer when participants read about an implied orientation that did not match the orientation of the previously seen picture than when the orientation matched. This suggests that a picture encountered 20 min earlier and incidental to the reading task influenced reading. These results have implications for theories of reading comprehension and embodied cognition.

Seeing with ears: Sightless humans’ perception of dog bark provides a test for structural rules in vocal communication

Prerecorded family dog (Canis familiaris) barks were played back to groups of congenitally sightless, sightless with prior visual experience, and sighted people (none of whom had ever owned a dog). We found that blind people without any previous canine visual experiences can categorize accurately various dog barks recorded in different contexts, and their results are very close to those of sighted people in characterizing the emotional content of barks. These findings suggest that humans can recognize some of the most important motivational states reflecting, for example, fear or aggression in a dog's bark without any visual experience. It is very likely that this result can be generalized to other mammalian species--that is, no visual experience of another individual is needed for recognizing some of the most important motivational states of the caller.

The cone inputs to colour appearance mechanisms

What computation does the human brain perform when we experience ‘red’, ‘green’, ‘yellow’, or ‘blue’? How does the human visual system combine the retinal cone signals (L, M, S cones) to yield these colour sensations? To address this question we ask observers to select the colour which appears ‘neither red nor green’ (yielding unique yellow and unique blue) or ‘neither yellow nor blue’ (yielding unique red and unique green). Since we obtain these unique hue settings at different luminance and saturation levels, we have numerous points in 3-dimensional (LMS) cone space that correspond to a particular hue. This allows us to determine quantitatively how the cone signals are related to a particular perceived hue. Our results show that the human visual system employs as least three chromatic mechanisms to yield the four unique hues and, to a first approximation, these mechanisms combine the (L,M,S) cone signals linearly. Furthermore, the variability between observers is relatively small when expressed in terms of preceptual errors. Our results add further weight to the idea that the colour vision system in adult human is able to recalibrate itself based on the prior visual experience and that our colour appearance mechanisms may be a consequence of environmental contraints.

Evidence for a Proprioception-Based Rapid On-Line Error Correction Mechanism for Hand Orientation during Reaching Movements in Blind Subjects

The contribution of visual experience to the perception and sensorimotor control of spatial orientation of the hand was investigated in blind subjects. In "orientation-matching" tasks, subjects aligned a match handle held in their right hand to a target handle held in their left hand and fixed in different orientations, with both arms outstretched. In "letter-posting" task 1, the same subjects reached out and simultaneously oriented their right hand to insert the match handle into a target slot fixed in the same range of orientations. Orientations were signaled proprioceptively by a reference handle held in the left hand. Final hand orientation errors were smaller when blind subjects simultaneously reached out and rotated their hand to insert the match handle into the target slot in letter-posting task 1 than when they held their arm extended and aligned the handles in the orientation-matching task. In letter-posting task 2, blind subjects first aligned their hand to the orientation of the target and then subsequently reached to the target with the instruction to not change hand orientation during reaching. Despite the instruction, subjects showed a reduction in absolute hand orientation error from the beginning to the end of the reach. In all tasks, performance of blind subjects was very similar to that of blindfolded normally sighted subjects. These findings provide the first evidence of an automatic on-line error-correction mechanism for hand orientation guided only by proprioceptive inputs during reaching in blind subjects, and reveal that the on-line mechanism does not depend on prior visual experience.

Tactile spatial working memory activates the dorsal extrastriate cortical pathway in congenitally blind individuals.

In sighted individuals, both the visual and tactile version of the same spatial working memory task elicited neural responses in the dorsal "where" cortical pathway (Ricciardi et al., 2006). Whether the neural response during the tactile working memory task is due to visually-based spatial imagery or rather reflects a more abstract, supramodal organization of the dorsal cortical pathway remains to be determined. To understand the role of visual experience on the functional organization of the dorsal cortical stream, using functional magnetic resonance imaging (fMRI) here we examined brain response in four individuals with congenital or early blindness and no visual recollection, while they performed the same tactile spatial working memory task, a one-back recognition of 2D and 3D matrices. The blind subjects showed a significant activation in bilateral posterior parietal cortex, dorsolateral and inferior prefrontal areas, precuneus, lateral occipital cortex, and cerebellum. Thus, dorsal occipito-parietal areas are involved in mental imagery dealing with spatial components in subjects without prior visual experience and in response to a non-visual task. These data indicate that recruitment of the dorsal cortical pathway in response to the tactile spatial working memory task is not mediated by visually-based imagery and that visual experience is not a prerequisite for the development of a more abstract functional organization of the dorsal stream. These findings, along with previous data indicating a similar supramodal functional organization within the ventral cortical pathway and the motion processing brain regions, may contribute to explain how individuals who are born deprived of sight are able to interact effectively with the surrounding world.

Effects of prior experience in raised line materials and prior visual experience in length estimations by blind people

The purpose of this research was to examine the role of expertise (as a result of previous training) in the use of raised line materials, and of visual experience by blind adults (congenitally, early and late blind), by means of tasks involving size estimation of common objects and length estimation. Results showed that, depending on the size of the objects, most participants were more successful in size estimations of common objects than in length estimations. They also showed an effect of visual experience in common object size estimation and an effect of expertise in length estimation. The results on length estimation suggested that, in this type of task, the advantage provided by prior expertise in raised line materials could surpass the one generally brought by the duration of visual experience. The findings suggest that blind people could improve their spatial mental imagery through being encouraged to use raised line materials.

Neural and behavioral correlates of drawing in an early blind painter: A case study

Humans rely heavily on vision to identify objects in the world and can create mental representations of the objects they encounter. Objects can also be identified and mentally represented through haptic exploration. However, it is unclear whether prior visual experience is necessary to generate these internal representations. Subject EA, an early blind artist, provides insight into this question. Like other blind individuals, EA captures the external world by touch. However, he is also able to reveal his internal representations through highly detailed drawings that are unequivocally understandable by a sighted person. We employed fMRI to investigate the neural correlates associated with EA's ability to transform tactilely explored three-dimensional objects into drawings and contrasted these findings with a series of control conditions (e.g. nonsensical scribbling as a sensory-motor control). Activation during drawing (compared to scribbling) occurred in brain areas normally associated with vision, including the striate cortex along with frontal and parietal cortical regions. Some of these areas showed overlap when EA was asked to mentally imagine the pictures he had to draw (albeit to a lesser anatomical extent and signal magnitude). These results have important implications as regards our understanding of the ways in which tactile information can generate mental representations of shapes and scenes in the absence of normal visual development. Furthermore, these findings suggest the occipital cortex plays a key role in supporting mental representations even without prior visual experience.

Understanding the developmental origins of primate face recognition: Theoretical commentary on Martin-Malivel and Okada (2007).

J. Martin-Malivel and K. Okada (2007, this issue) reported that chimpanzees raised with extensive social contact with humans show face discrimination abilities for human faces that exceed those for conspecific faces. Martin-Malivel and Okada have placed this finding in the theoretical context of the relative role of experience and innate face representations. The present article discusses the logic of the various styles of studies relevant to this question--considering primates without prior visual experience, sensitive periods, perceptual narrowing, childhood development, other-species effects, other-race effects, social quality of experience with nonconspecifics, and perceived social group membership--and also reviews the key current data. A case is made that there is still a long way to go in understanding whether there is an innate representation of conspecific faces, how tightly tuned any such representation is to conspecific morphology, and how experience obtained during different age brackets (e.g., infancy versus adulthood) affects discrimination and interacts with any innate representation.

Viewpoint and Orientation Influence Picture Recognition in the Blind

In the first three experiments, subjects felt solid geometrical forms and matched raised-line pictures to the objects. Performance was best in experiment 1 for top views, with shorter response latencies than for side views, front views, or 3-D views with foreshortening. In a second experiment with blind participants, matching accuracy was not significantly affected by prior visual experience, but speed advantages were found for top views, with 3-D views also yielding better matching accuracy than side views. There were no performance advantages for pictures of objects with a constant cross section in the vertical axis. The early-blind participants had lower performance for side and frontal views. The objects were rotated to oblique orientations in experiment 3. Early-blind subjects performed worse than the other subjects given object rotation. Visual experience with pictures of objects at many angles could facilitate identification at oblique orientations. In experiment 5 with blindfolded sighted subjects, tangible pictures were used as targets and as choices. The results yielded superior overall performance for 3-D views (mean, M = 74% correct) and much lower matching accuracy for top views as targets (M = 58% correct). Performance was highest when the target and matching viewpoint were identical, but 3-D views (M = 96% correct) were still far better than top views. The accuracy advantage of the top views also disappeared when more complex objects were tested in experiment 6. Alternative theoretical implications of the results are discussed.

The cone inputs to the unique-hue mechanisms

Our aim was to characterise the chromatic mechanisms that yield the four unique hues: red, green, yellow and blue. We measured the null planes for all four unique hues and report the following two main results. (1) We confirm that three chromatic mechanisms are required to account for the four unique hues. These three chromatic mechanisms do not coincide with the chromatic tuning found in parvocellular LGN neurones, i.e., neurones tuned to L − M and S − (L + M); these subcortical chromatic mechanisms are hence not the neural substrate of the perceptual unique hues and further higher-order colour mechanisms need to be postulated. Our results are consistent with the idea that the two higher-order colour mechanisms that yield unique red and unique green respectively combine the incremental and decremental responses of the subcortical chromatic mechanisms with different weights. In contrast, unique yellow and unique blue can be explained by postulating a single higher-order chromatic mechanism that combines the incremental and decremental subcortical chromatic responses with similar weights. (2) The variability between observers is small when expressed in terms of perceptual errors, which is consistent with the hypothesis that the colour vision system in adult humans is able to recalibrate itself based on prior visual experience.

Enhanced self-localization by auditory cues in blind humans

Purpose. Investigate the involvement of auditory spatial compensation, which is observed in blind humans, in self-localization processes.Method. Sighted and early-blind subjects had to indicate, on a two-dimensional view of the experimental room, the position where they previously sat and had passively listened to auditory spatial cues. Two different environments were distinguished. In a first session, auditory cues (i.e., white broadband sounds) were displayed successively in a dark anechoic room. This condition was defined as a simple acoustic environment. In a second session, four different auditory cues were displayed simultaneously at regular intervals in an experimental room, where echo cues were salient. This condition, which is more reminiscent of the natural situation, was described as a complex acoustic environment.Results. Self-localization capacities were significantly better in early-blind individuals than in sighted subjects, whatever the type of acoustic environment.Conclusions. Auditory compensation leads to improved self-localization capacities in early-blind humans and indicates that prior visual experience is not essential for the development of spatial competence.