Size Constancy Research Articles

Representation and the active consumer

One of the central tasks for naturalistic theories of representation is to say what it takes for something to be a representation, and some leading theories have been criticised for being too liberal. Prominent discussions of this problem have proposed a producer-oriented solution; it is argued that representations must be produced by systems employing perceptual constancy mechanisms. However, representations may be produced by simple transducers if they are consumed in the right way. It is characteristic of representations to be consumed by systems which are capable of independent action. This paper defends this claim; discusses more precise, naturalistic formulations; and shows how it can illuminate the explanatory payoffs which science achieves by appealing to representation.

Shape and Size Constancy in Consumer Virtual Reality

Shape and Size Constancy in Consumer Virtual Reality

Shape constancy in anaglyphs: Effects of drawing training

Shape constancy in anaglyphs: Effects of drawing training

Spectral contrast effects produced by competing speech contexts.

The long-term spectrum of a preceding sentence can alter the perception of a following speech sound in a contrastive manner. This speech context effect contributes to our ability to extract reliable spectral characteristics of the surrounding acoustic environment and to compensate for the voice characteristics of different speakers or spectral colorations in different listening environments to maintain perceptual constancy. The extent to which such effects are mediated by low-level "automatic" processes, or require directed attention, remains unknown. This study investigated spectral context effects by measuring the effects of two competing sentences on the phoneme category boundary between /i/ and /ε/ in a following target word, while directing listeners' attention to one or the other context sentence. Spatial separation of the context sentences was achieved either by presenting them to different ears, or by presenting them to both ears but imposing an interaural time difference (ITD) between the ears. The results confirmed large context effects based on ear of presentation. Smaller effects were observed based on either ITD or attention. The results, combined with predictions from a two-stage model, suggest that ear-specific factors dominate speech context effects but that the effects can be modulated by higher-level features, such as perceived location, and by attention. (PsycINFO Database Record

The Neural Correlate Of Size Constancy Measured With SSVEP In Virtual Reality

The Neural Correlate Of Size Constancy Measured With SSVEP In Virtual Reality

Effects of cyclic changes in population size on neutral genetic diversity.

Recurrent changes in population size are often observed in nature, influencing the efficiency of selection and consequently affecting organismal evolution. Thus, it is important to know whether such changes occurred in the past history of a focal population of evolutionary interests. Here, we focused on cyclic changes in population size and investigated the distributional properties of Tajima's D and its power to distinguish a cyclic change model compared with the standard neutral model, changing the frequency and magnitude of the cyclic change. With very low or very high frequencies of the cycle, the distribution of Tajima's D was similar to that in a constant size population, as demonstrated by previous theoretical works. Otherwise, its mean was negative or positive, and its variance was smaller or larger depending on the time of sampling. The detection rate of the cyclic change against the constancy in size by Tajima's D depended on the sample size, the number of loci, and the time of sampling in addition to the frequency and amplitude of the cycle. Using sequence data of several tens of loci, the detection rate was fairly high if the frequency was intermediate and the sampling was made when population size was large; otherwise, the detection rate was not high. We also found that cyclic change could be discriminated from simple expansion or shrinkage of a population by Tajima's D only if the frequency was in a limited range and the sampling was made when the population was large.

Auditory enhancement and the role of spectral resolution in normal-hearing listeners and cochlear-implant users.

Detection of a target tone in a simultaneous multi-tone masker can be improved by preceding the stimulus with the masker alone. The mechanisms underlying this auditory enhancement effect may enable the efficient detection of new acoustic events and may help to produce perceptual constancy under varying acoustic conditions. Previous work in cochlear-implant (CI) users has suggested reduced or absent enhancement, due perhaps to poor spatial resolution in the cochlea. This study used a supra-threshold enhancement paradigm that in normal-hearing listeners results in large enhancement effects, exceeding 20 dB. Results from vocoder simulations using normal-hearing listeners showed that near-normal enhancement was observed if the simulated spread of excitation was limited to spectral slopes no shallower than 24 dB/oct. No significant enhancement was observed on average in CI users with their clinical monopolar stimulation strategy. The variability in enhancement between CI users, and between electrodes in a single CI user, could not be explained by the spread of excitation, as estimated from auditory nerve evoked potentials. Enhancement remained small, but did reach statistical significance, under the narrower partial-tripolar stimulation strategy. The results suggest that enhancement may be at least partially restored by improvements in the spatial resolution of current CIs.

East of West, West of East: a matter of global and local identity.

Research is a very personal matter. On the basis of experiences in different countries with researchers from different cultures over many years, some observations will be described. The conceptual frame of this attempt is to look for anthropological universals and cultural specifics. Much can be learned from spatial representations in the arts. Whereas in the West since Renaissance time the central perspective has become dominant in visual art, in Eastern landscape paintings the "floating view" is typical. The claim that the central perspective corresponds to geometric laws and matches how we see the world is misleading for at least two reasons: It violates mechanisms of size constancy, and the visual world is spatially reduced in pictures to the perifoveal region only. Research on spatial attention has disclosed two different attentional systems being responsible either for near-fovea vision or for the far periphery. This fundamental principle as a global characteristic of visual processing is neglected in Western art. In Eastern art with a floating view geometric laws are violated, and different potential perspectives are integrated within a holistic pattern. The semantics of what shall be expressed becomes important irrespective of physical parameters. The latter may also create the unique phenomenon of becoming subjectively part of the picture confirming personal identity. Cultural specifics like in the arts (what one might expect) can surprisingly also be observed in theoretical considerations about visual processing. Whereas in the tradition of Western science visual percepts are built up with local elements like feature detectors, in an important Chinese theory global topological features are analyzed first. An important task of the brain is to create the identity of a percept on the basis of spatially and temporally distributed neural activities. It is, thus, an important theoretical question how to deal with the challenge to create and maintain the identity of a percept for some time. It is suggested that one should leave behind a monocausal reasoning for such explanations but adopt for analytical strategies the concept of complementarity as a generative principle.

The nature of shape constancy mechanisms as revealed by shape priming.

Five shape priming experiments are reported in which the target was either a five- or six-sided line-drawn figure and participants made a speeded two-alternative forced-choice judgment about the target's number of sides. On priming trials, the target was preceded by a briefly presented smaller line figure (the prime) and performance on these trials was gauged relative to a no-prime condition. In the first two experiments, primes were rendered invisible by the presentation of a backwards visual noise mask, respectively for a short (∼40 ms) or long duration (∼93 ms). No reliable priming effects arose under masked conditions. When these experiments were repeated without the mask, participants were speeded when the prime and target were related by a rigid through-the-plane rotation but not when the prime was a nonrigid, stretched version of the target. The same pattern of priming effects arose when, in a final experiment, novel irregular shapes were used. Collectively, the data reveal the operation of shape constancy mechanisms that are particularly sensitive to shape rigidity. The findings suggest that the visual system attempts to secure a correspondence between the rapid and successive presentations of the prime and the target by matching shapes according to a rigidity constraint.

Selective Attention and Working Memory Under Spatial Disorientation in a Flight Simulator

ABSTRACTObjective: The aim of this study was to test the effects of visual and vestibular spatial disorientation on the cognitive performance of military aviators while they were piloting a flight simulator.Background: Spatial disorientation (SD), the inability to correctly determine the position and orientation of the aircraft in relation to the ground, poses a serious threat in aviation and can impair the cognitive performance of pilots while flying. More evidence is needed on the effects of visual and vestibular SD on cognition in flight simulators.Method: Pilots performed an auditory selective attention (duration discrimination) task (Experiment 1, N = 16) or an auditory working memory (N-back) task (Experiment 2, N = 16) while completing 6 different flight profiles in the disorientation and control conditions in the GYRO-IPT flight simulator. The flight scenarios included 3 visual illusions (false horizon, shape constancy, size constancy) and 3 vestibular illusions (somatogyral illusion, Coriolis effect, the leans).Results: In both experiments the cognitive performance (task accuracy) decreased for flight profiles with the leans illusion. Also, the flight performance (measured as the number of control reversal errors) was worse for the false horizon illusion and for the somatogyral illusion in both experiments.Conclusion: The results suggest that SD, particularly the vestibular illusion of the leans, can impair selective attention and working memory processes.

The Way Things Look: a Defence of Content

How does perceptual experience disclose the world to our view? In the first introductory section, I set up a contrast between the representational and the purely relational conception of perceptual experience. In the second section, I discuss an argument given by Charles Travis (Mind 113: 57–94, 2004) against perceptual content. The third section is devoted to the phenomenon of perceptual constancy: in 3.1 I describe the phenomenon. In 3.2 I argue that the description given suggests a phenomenological distinction that can be deployed for a defence of content. In 3.3 I compare and contrast my view of perceptual content with that of Susanna Schellenberg (The Journal of Philosophy 105(02): 55–84, 2008). Finally (3.4), I support my conception of content by means of an argument that links content to the way in which the mind-independent nature of material objects is manifest in perceptual experience.

Proprioceptive Distance Cues Restore Perfect Size Constancy in Grasping, but Not Perception, When Vision Is Limited

Our brain integrates information from multiple modalities in the control of behavior. When information from one sensory source is compromised, information from another source can compensate for the loss. What is not clear is whether the nature of this multisensory integration and the re-weighting of different sources of sensory information are the same across different control systems. Here, we investigated whether proprioceptive distance information (position sense of body parts) can compensate for the loss of visual distance cues that support size constancy in perception (mediated by the ventral visual stream) [1, 2] versus size constancy in grasping (mediated by the dorsal visual stream) [3-6], in which the real-world size of an object is computed despite changes in viewing distance. We found that there was perfect size constancy in both perception and grasping in a full-viewing condition (lights on, binocular viewing) and that size constancy in both tasks was dramatically disrupted in the restricted-viewing condition (lights off; monocular viewing of the same but luminescent object through a 1-mm pinhole). Importantly, in the restricted-viewing condition, proprioceptive cues about viewing distance originating from the non-grasping limb (experiment 1) or the inclination of the torso and/or the elbow angle of the grasping limb (experiment 2) compensated for the loss of visual distance cues to enable a complete restoration of size constancy in grasping but only a modest improvement of size constancy in perception. This suggests that the weighting of different sources of sensory information varies as a function of the control system being used.

Perceptual Constancy in the Reproduction of Virtual Tactile Textures With Surface Displays

For very rough surfaces, friction-induced vibrations contain frequencies that change in proportion to sliding speed. Given the poor capacity of the somatosensory system to discriminate frequencies, this fact raises the question of how accurately finger sliding speed must be known during the reproduction of virtual textures with a surface tactile display. During active touch, ten observers were asked to discriminate texture recordings corresponding to different speeds. The samples were constructed from a common texture, which was resampled at various frequencies to give a set of stimuli of different swiping speeds. In trials, they swiped their finger in rapid succession over a glass plate, which vibrated to accurately reproduce three texture recordings. Two of these recordings were identical and a third differed in that the sample represented a texture swiped at a speed different from the other two. Observers identified which of the three samples felt different. For a metal mesh texture recording, seven observers reported differences when the speed varied by 60, 80, and 100mm/s while the other three did not reach a discrimination threshold. For a finer leather chamois texture recording, thresholds were never reached in the 100mm/s range. These results show that the need for high-accuracy measurement of swiping speed during texture reproduction may actually be quite limited compared to what is commonly found in the literature.

Varying acoustic-phonemic ambiguity reveals that talker normalization is obligatory in speech processing.

The nondeterministic relationship between speech acoustics and abstract phonemic representations imposes a challenge for listeners to maintain perceptual constancy despite the highly variable acoustic realization of speech. Talker normalization facilitates speech processing by reducing the degrees of freedom for mapping between encountered speech and phonemic representations. While this process has been proposed to facilitate the perception of ambiguous speech sounds, it is currently unknown whether talker normalization is affected by the degree of potential ambiguity in acoustic-phonemic mapping. We explored the effects of talker normalization on speech processing in a series of speeded classification paradigms, parametrically manipulating the potential for inconsistent acoustic-phonemic relationships across talkers for both consonants and vowels. Listeners identified words with varying potential acoustic-phonemic ambiguity across talkers (e.g., beet/boat vs. boot/boat) spoken by single or mixed talkers. Auditory categorization of words was always slower when listening to mixed talkers compared to a single talker, even when there was no potential acoustic ambiguity between target sounds. Moreover, the processing cost imposed by mixed talkers was greatest when words had the most potential acoustic-phonemic overlap across talkers. Models of acoustic dissimilarity between target speech sounds did not account for the pattern of results. These results suggest (a) that talker normalization incurs the greatest processing cost when disambiguating highly confusable sounds and (b) that talker normalization appears to be an obligatory component of speech perception, taking place even when the acoustic-phonemic relationships across sounds are unambiguous.

Transsaccadic transfer of distortion adaptation in a natural environment.

Spatially varying distortions in optical elements-for instance prisms and progressive power lenses-modulate the visual world disparately in different visual areas. Saccadic eye movements in such a complexly distorted environment thereby continuously alter the retinal location of the distortions. Yet the visual system achieves perceptual constancy by compensating for distortions irrespective of their retinal relocations at different fixations. Here, we assessed whether the visual system retains its plasticity to distortions across saccades to attain stability. Specifically, we tapped into reference frames of geometric skew-adaptation aftereffects to evaluate the transfer of retinotopic and spatiotopic distortion information across saccades. Adaptation to skew distortion of natural-image content was tested at retinotopic and spatiotopic locations after a saccade was executed between adaptation and test phases. The skew-adaptation information was partially transferred to a new fixation after a saccade. Significant adaptation aftereffects were obtained at both retinotopic and spatiotopic locations. Conceivably, spatiotopic information was used to counterbalance the saccadic retinal shifts of the distortions. Therefore, distortion processing in a natural visual world does not start anew at each fixation; rather, retinotopic and spatiotopic skew information acquired at previous fixations are preserved to mediate stable perception during eye movements.

Phonological feature-based speech recognition system for pronunciation training in non-native language learning.

The authors address the question whether phonological features can be used effectively in an automatic speech recognition (ASR) system for pronunciation training in non-native language (L2) learning. Computer-aided pronunciation training consists of two essential tasks-detecting mispronunciations and providing corrective feedback, usually either on the basis of full words or phonemes. Phonemes, however, can be further disassembled into phonological features, which in turn define groups of phonemes. A phonological feature-based ASR system allows the authors to perform a sub-phonemic analysis at feature level, providing a more effective feedback to reach the acoustic goal and perceptual constancy. Furthermore, phonological features provide a structured way for analysing the types of errors a learner makes, and can readily convey which pronunciations need improvement. This paper presents the authors implementation of such an ASR system using deep neural networks as an acoustic model, and its use for detecting mispronunciations, analysing errors, and rendering corrective feedback. Quantitative as well as qualitative evaluations are carried out for German and Italian learners of English. In addition to achieving high accuracy of mispronunciation detection, the system also provides accurate diagnosis of errors.

SERS polarization-dependent effects for an ordered 3D plasmonic tilted silver nanorod array.

Hexagonal close-packed tilted Ag nanorod arrays that exhibit excellent uniformity and reproducibility were prepared. The tilt angle was easily controlled by regulating the sputtering angle, accompanied by a reduction and constancy in the gap size of adjacent nanorods, which is 30° and 90° relative to the sputtering direction. The surface enhanced Raman spectroscopy (SERS) technique was used to characterize the interaction of tilted Ag nanorod arrays with polarized laser excitation. Interestingly, the SERS polarization-dependence increased with increasing tilt angle of the Ag nanorods. To elucidate the essential factors responsible for this SERS result, three-dimensional (3D) electromagnetic enhancement distribution for the proposed system was numerically simulated based on p- and s-polarization excitation. Most importantly, the fundamental reasons for the polarization dependence of SERS were obtained by a quantitative 3D numerical simulation of hotspot distribution for adjacent nanorods.

The Influence of Visual Perceptual Constancy on Attracting Attention to Digital Images on Advertising Posters = تأثير الثبات الإدراكي البصري على زيادة جذب الانتباه للصورة الرقمية في الملصق الإعلاني

الفن الإسلامي هو واحد من أعظم إنجازات الثقافة الإسلامية في مصر. يتناول هذا البحث الأنماط الهندسية الإسلامية في مسجد ابن طولون بالقاهرة بمصر وبعض تقنيات الباتشوورک لإظهار مدى أهمية الدمج بينهما في الموضة المعاصرة. يتضمن البحث 14 تصميم لأزياء معاصرة للسيدات للفئة العمرية (25-35 سنة). ويظهر التحليل الإحصائي أن التصميمات تعبر عن الزخارف الهندسية في مسجد ابن طولون وتقنيات الباتشوورک بنسبة 96٪. ويظهر أيضا أن التصميمات مناسبة للسيدات من الفئة العمرية (25-35 سنة) بنسبة 95٪. ويبين التحليل الاحصائي أن التصميم 4 له أدنى متوسط في حين أن التصميم 1 له أعلى متوسط.

Smelling objects

Objects are central to perception and our interactions with the world. We perceive the world as parsed into discrete entities that instantiate particular properties, and these items capture our attention and shape how we interact with the environment. Recently there has been some debate about whether the sense of smell allows us to perceive odours as discrete objects, with some suggesting that olfaction is aspatial and doesn’t allow for object-individuation. This paper offers two empirically tractable criteria for assessing whether particular objects are exhibited in perceptual experience—(1) susceptibility to figure-ground segregation and (2) perceptual constancies—and argues that these criteria are fulfilled by olfactory perception, and thus there are olfactory objects. I argue that there are, in fact, two different ways that olfaction allows for figure-ground segregation. First, I look at various Gestalt grouping principles, which are thought to govern when features are perceived as grouped into structured wholes, segregated from everything around them. I argue that these principles apply to olfactory experience, providing evidence of non-spatial figure-ground segregation. Second, I defend the contentious idea that a spatial variety of figure-ground segregation can also occur in olfaction. To see this, however, we need to look to empirical evidence showing that tactile stimulation and bodily movements play a crucial role in olfactory phenomenology. Finally, I draw on empirical evidence and olfactory phenomenology to argue that there are perceptual constancies in olfactory experience, allowing us to perceive odours as coherent objects that survive shifts in our perspectives on the world.

How we perceive our own retina.

Ever since the days of René Descartes, in the seventeenth century, the search for the relationship between subjective perception and neural activity has been an ongoing challenge. In neuroscience, an approach to the problem via the visual system has produced a paradigm using perceptual suppression, changing with time. Cortical areas in which the neural activity was modulated in temporal correlation with this percept could be traced. Although these areas may lead directly to perception, such temporal correlation of neural activity does not suffice as ultimate proof that they actually do so. In this article, I will use a different method to show that, for the perception of our own retina, any brain area leading directly to this perception also needs to represent the retina without distortion. Furthermore, I will demonstrate that the phenomenon of size constancy must be realized in this area.