Veridical Representation Research Articles

The neural encoding of self-generated and externally applied movement: implications for the perception of self-motion and spatial memory

The vestibular system is vital for maintaining an accurate representation of self-motion. As one moves (or is moved) toward a new place in the environment, signals from the vestibular sensors are relayed to higher-order centers. It is generally assumed the vestibular system provides a veridical representation of head motion to these centers for the perception of self-motion and spatial memory. In support of this idea, evidence from lesion studies suggests that vestibular inputs are required for the directional tuning of head direction cells in the limbic system as well as neurons in areas of multimodal association cortex. However, recent investigations in monkeys and mice challenge the notion that early vestibular pathways encode an absolute representation of head motion. Instead, processing at the first central stage is inherently multimodal. This minireview highlights recent progress that has been made towards understanding how the brain processes and interprets self-motion signals encoded by the vestibular otoliths and semicircular canals during everyday life. The following interrelated questions are considered. What information is available to the higher-order centers that contribute to self-motion perception? How do we distinguish between our own self-generated movements and those of the external world? And lastly, what are the implications of differences in the processing of these active vs. passive movements for spatial memory?

Internet Addiction Test (IAT): Which is the Best Factorial Solution?

BackgroundThe Internet Addiction Test (IAT) by Kimberly Young is one of the most utilized diagnostic instruments for Internet addiction. Although many studies have documented psychometric properties of the IAT, consensus on the optimal overall structure of the instrument has yet to emerge since previous analyses yielded markedly different factor analytic results.ObjectiveThe objective of this study was to evaluate the psychometric properties of the Italian version of the IAT, specifically testing the factor structure stability across cultures.MethodsIn order to determine the dimensional structure underlying the questionnaire, both exploratory and confirmatory factor analyses were performed. The reliability of the questionnaire was computed by the Cronbach alpha coefficient.ResultsData analyses were conducted on a sample of 485 college students (32.3%, 157/485 males and 67.7%, 328/485 females) with a mean age of 24.05 years (SD 7.3, range 17-47). Results showed 176/485 (36.3%) participants with IAT score from 40 to 69, revealing excessive Internet use, and 11/485 (1.9%) participants with IAT score from 70 to 100, suggesting significant problems because of Internet use. The IAT Italian version showed good psychometric properties, in terms of internal consistency and factorial validity. Alpha values were satisfactory for both the one-factor solution (Cronbach alpha=.91), and the two-factor solution (Cronbach alpha=.88 and Cronbach alpha=.79). The one-factor solution comprised 20 items, explaining 36.18% of the variance. The two-factor solution, accounting for 42.15% of the variance, showed 11 items loading on Factor 1 (Emotional and Cognitive Preoccupation with the Internet) and 7 items on Factor 2 (Loss of Control and Interference with Daily Life). Goodness-of-fit indexes (NNFI: Non-Normed Fit Index; CFI: Comparative Fit Index; RMSEA: Root Mean Square Error of Approximation; SRMR: Standardized Root Mean Square Residual) from confirmatory factor analyses conducted on a random half subsample of participants (n=243) were satisfactory in both factorial solutions: two-factor model (χ2 132= 354.17, P<.001, χ2/df=2.68, NNFI=.99, CFI=.99, RMSEA=.02 [90% CI 0.000-0.038], and SRMR=.07), and one-factor model (χ2 169=483.79, P<.001, χ2/df=2.86, NNFI=.98, CFI=.99, RMSEA=.02 [90% CI 0.000-0.039], and SRMR=.07).ConclusionsOur study was aimed at determining the most parsimonious and veridical representation of the structure of Internet addiction as measured by the IAT. Based on our findings, support was provided for both single and two-factor models, with slightly strong support for the bidimensionality of the instrument. Given the inconsistency of the factor analytic literature of the IAT, researchers should exercise caution when using the instrument, dividing the scale into factors or subscales. Additional research examining the cross-cultural stability of factor solutions is still needed.

Temporal memory averaging and post-encoding alterations in temporal expectation

Recent work in our lab has demonstrated that rats trained to associate two different reinforcement delays with two different cues will generate a scalar temporal expectation at a time between these delays when presented with the cue compound. This work demonstrates that rats will integrate distinct temporal memories at retrieval, revealing that temporal expectation need not be a veridical representation of experience. Following from this recognition that processes occurring at or after memory retrieval may transform or bias temporal expectations, we suggest that previous pharmacological work that had been interpreted as resulting from sensorial, or clock-speed, changes, may be alternatively interpreted as resulting from mnemonic alterations. We end with a brief review of the impact of post-encoding alterations of memory on behavior other than timing.This article is part of a special issue entitled: SQAB 2012 Special Issue.

Brain and the gaze: on the active boundaries of vision

How do we gain access to things as they are? Although we routinely take our self-made pictures to be veridical representations of reality, in actuality we choose (albeit unwittingly) or construct what we see. By movements of the eyes, the direction of our gaze, we create meaning. In Brain and the Gaze, Jan Lauwereyns offers a novel reformulation of perception and its neural underpinnings, focusing on the active nature of perception. In his investigation of active perception and its brain mechanisms, Lauwereyns offers the gaze as the principal paradigm for perception. In a radically integrative account, grounded in neuroscience but drawing on insights from philosophy and psychology, he discusses the dynamic and constrained nature of perception; the complex information processing at the level of the retina; the active nature of vision; the intensive nature of representations; the gaze of others as visual stimulus; and the intentionality of vision and consciousness. An engaging point of entry to the cognitive neuroscience of perception, written for neuroscientists but illuminated by insights from thinkers ranging from William James to Slavoj Zizek, Brain and the Gaze will give new impetus to research and theory in the field.

Straight or curved? From deterministic to probabilistic models of 3D motion perception

Straight or curved? From deterministic to probabilistic models of 3D motion perception

Gone in a flash: manipulation of audiovisual temporal integration using transcranial magnetic stimulation

While converging evidence implicates the right inferior parietal lobule in audiovisual integration, its role has not been fully elucidated by direct manipulation of cortical activity. Replicating and extending an experiment initially reported by Kamke et al. (2012), we employed the sound-induced flash illusion, in which a single visual flash, when accompanied by two auditory tones, is misperceived as multiple flashes (Wilson, 1987; Shams et al., 2000). Slow repetitive (1 Hz) TMS administered to the right angular gyrus, but not the right supramarginal gyrus, induced a transient decrease in the Peak Perceived Flashes (PPF), reflecting reduced susceptibility to the illusion. This finding independently confirms that perturbation of networks involved in multisensory integration can result in a more veridical representation of asynchronous auditory and visual events and that cross-modal integration is an active process in which the objective is the identification of a meaningful constellation of inputs, at times at the expense of accuracy.

Perceptual representations of phonotactically illegal syllables

Listeners often categorize phonotactically illegal sequences (e.g., /dla/ in English) as phonemically similar legal ones (e.g., /gla/). In an earlier investigation of such an effect in Japanese, Dehaene-Lambertz, Dupoux, and Gout (2000) did not observe a mismatch negativity in response to deviant, illegal sequences, and therefore argued that phonotactics constrain early perceptual processing. In the present study, using a priming paradigm, we compared the event-related potentials elicited by Legal targets (e.g., /gla/) preceded by (1) phonemically distinct Control primes (e.g., /kla/), (2) different tokens of Identity primes (e.g., /gla/), and (3) phonotactically Illegal Test primes (e.g., /dla/). Targets elicited a larger positivity 200-350 ms after onset when preceded by Illegal Test primes or phonemically distinct Control primes, as compared to Identity primes. Later portions of the waveforms (350-600 ms) did not differ for targets preceded by Identity and Illegal Test primes, and the similarity ratings also did not differ in these conditions. These data support a model of speech perception in which veridical representations of phoneme sequences are not only generated during processing, but also are maintained in a manner that affects perceptual processing of subsequent speech sounds.

Linear mapping of numbers onto space requires attention

Mapping of number onto space is fundamental to mathematics and measurement. Previous research suggests that while typical adults with mathematical schooling map numbers veridically onto a linear scale, pre-school children and adults without formal mathematics training, as well as individuals with dyscalculia, show strong compressive, logarithmic-like non-linearities when mapping both symbolic and non-symbolic numbers onto the numberline. Here we show that the use of the linear scale is dependent on attentional resources. We asked typical adults to position clouds of dots on a numberline of various lengths. In agreement with previous research, they did so veridically under normal conditions, but when asked to perform a concurrent attentionally-demanding conjunction task, the mapping followed a compressive, non-linear function. We model the non-linearity both by the commonly assumed logarithmic transform, and also with a Bayesian model of central tendency. These results suggest that veridical representation numerosity requires attentional mechanisms.

Hierarchical Encoding in Visual Working Memory

Influential models of visual working memory treat each item to be stored as an independent unit and assume that there are no interactions between items. However, real-world displays have structure that provides higher-order constraints on the items to be remembered. Even in the case of a display of simple colored circles, observers can compute statistics, such as mean circle size, to obtain an overall summary of the display. We examined the influence of such an ensemble statistic on visual working memory. We report evidence that the remembered size of each individual item in a display is biased toward the mean size of the set of items in the same color and the mean size of all items in the display. This suggests that visual working memory is constructive, encoding displays at multiple levels of abstraction and integrating across these levels, rather than maintaining a veridical representation of each item independently.

Recognition Alters the Spatial Pattern of fMRI Activation in Early Retinotopic Cortex

Early retinotopic cortex has traditionally been viewed as containing a veridical representation of the low-level properties of the image, not imbued by high-level interpretation and meaning. Yet several recent results indicate that neural representations in early retinotopic cortex reflect not just the sensory properties of the image, but also the perceived size and brightness of image regions. Here we used functional magnetic resonance imaging pattern analyses to ask whether the representation of an object in early retinotopic cortex changes when the object is recognized compared with when the same stimulus is presented but not recognized. Our data confirmed this hypothesis: the pattern of response in early retinotopic visual cortex to a two-tone "Mooney" image of an object was more similar to the response to the full grayscale photo version of the same image when observers knew what the two-tone image represented than when they did not. Further, in a second experiment, high-level interpretations actually overrode bottom-up stimulus information, such that the pattern of response in early retinotopic cortex to an identified two-tone image was more similar to the response to the photographic version of that stimulus than it was to the response to the identical two-tone image when it was not identified. Our findings are consistent with prior results indicating that perceived size and brightness affect representations in early retinotopic visual cortex and, further, show that even higher-level information--knowledge of object identity--also affects the representation of an object in early retinotopic cortex.

Category-based errors and the accessibility of unbiased spatial memories: A retrieval model.

Studies have consistently shown a spatial memory bias such that a target location is remembered toward the prototypical location of the region to which the target belongs, indicating a blending between the target's specific information and the generic information of its region. The authors investigated whether people retain a veridical representation of a target location after a delay by determining the locus of the blending (during encoding, delay, or retrieval). To examine accessibility to the original target location, they used a recognition task, which is less demanding than the traditional reproduction procedure. The results showed that participants were able to recognize the original position of a target over their own biased recalled position after both a short (1,500 ms) and a longer (5,000 ms) delay. These findings reveal that spatial memories can be undistorted despite distorted recall responses. Results are discussed in terms of J. Huttenlocher, L. V. Hedges, and S. Duncan's (1991) category adjustment model.

Optimal Predictions in Everyday Cognition: The Wisdom of Individuals or Crowds?

Griffiths and Tenenbaum (2006) asked individuals to make predictions about the duration or extent of everyday events (e.g., cake baking times), and reported that predictions were optimal, employing Bayesian inference based on veridical prior distributions. Although the predictions conformed strikingly to statistics of the world, they reflect averages over many individuals. On the conjecture that the accuracy of the group response is chiefly a consequence of aggregating across individuals, we constructed simple, heuristic approximations to the Bayesian model premised on the hypothesis that individuals have access merely to a sample of k instances drawn from the relevant distribution. The accuracy of the group response reported by Griffiths and Tenenbaum could be accounted for by supposing that individuals each utilize only two instances. Moreover, the variability of the group data is more consistent with this small-sample hypothesis than with the hypothesis that people utilize veridical or nearly veridical representations of the underlying prior distributions. Our analyses lead to a qualitatively different view of how individuals reason from past experience than the view espoused by Griffiths and Tenenbaum.

Some problems for representations of brain organization based on activation in functional imaging

Functional brain imaging has overshadowed traditional lesion studies in becoming the dominant approach to the study of brain-behavior relationships. The proponents of functional imaging studies frequently argue that this approach provides an advantage over lesion studies by observing normal brain activity in vivo without the disruptive effects of brain damage. However, the enthusiastic onslaught of brain images, frequently presented as veridical representations of mental function, has sometimes overwhelmed some basic facts about brain organization repeatedly observed over more than a century. In particular, the lateralization of speech and language to the left cerebral hemisphere in over 90% of the right-handed population does not appear to have been taken as a serious constraint in the interpretation of imaging results in studies of these functions. This paper reviews a number of areas in which standard activation assumptions yield results that are at odds with clinical experience. The activation approach will be contrasted with a performance-based analysis of functional image data, which, at least in the case of speech production, yields results in better agreement with lesion data. Functional imaging represents enormous opportunities for understanding brain-behavior relationships, but at the present level of understanding of what is being represented in such images, it is premature to adhere to a single approach based on the strong but questionable assumptions inherent in most activation studies.

Wittgenstein, Pretend Play and the Transferred Use of Language

This essay sketches the potential implications of Wittgensteinian thought for conceptualizations of socalled fictive mental states, e.g. mental calculating, imagination, pretend play, as they are currently discussed in developmental psychology and philosophy of mind. In developmental psychology the young child's pretend play and make‐belief are seen as a manifestation of the command of an underlying individualistic “theory of mind”. When saying “This banana is a telephone” the child's mind entertains simultaneously two mental representations, a primary or veridical representation about the real properties of banana's and a pretend representation. It is the task of psychology to explain how this “double knowledge” does not result in conceptual chaos. Various sorts of internal mechanisms are postulated. In this essay it is argued that the threat of chaos is misconceived, and that the solutions are irrelevant. Following Wittgenstein's sparse remarks about the secondary sense of words, I argue that pretend language does not refer to underlying individual mental representations but to the child's creative transference of words used in one, primary, domain of application to another, secondary domain. The command and use of the secondary domain logically presupposes the command and use of the primary domain. Since the latter domain is necessarily public and social, fictive mental states cannot be dealt with purely individualistically as current mentalism assumes.

Combined smooth and saccadic ocular pursuit during the transient occlusion of a moving visual object

Accurate ocular pursuit during a transient occlusion interval would minimize retinal position and velocity error, and could provide an advantage when discriminating object characteristics at reappearance. This study was designed to examine how the smooth and saccadic response extrapolates the trajectory of a moving visual object during a transient occlusion. We confirmed that subjects could not maintain unity gain smooth pursuit during the transient occlusion. Eye velocity decayed significantly without visual feedback but then in the majority of subjects, there was a recovery that brought eye velocity back towards object velocity. However, eye velocity did not increase to a level that eliminated the developing position error. Subjects corrected for the resulting error in eye position by releasing saccades that generally placed the eye ahead of the occluded object's extrapolated position. The majority of saccadic correction occurred between 220 and 600 ms of the occlusion interval, and when combined with the smooth response enabled accurate pursuit of a 10 degrees/s object for up to 1,200 ms of occlusion. The lack of saccadic correction after 600 ms of occlusion combined with the reduced eye velocity resulted in significant undershoot of eye position at the moment of object reappearance when pursuing an 18 degrees/s object. We suggest that extra-retinal information regarding eye velocity and smooth eye displacement could be available from a continually updating efference copy of eye motion in MST, whereas a veridical representation of extrapolated object velocity and displacement could be obtained from persistent activity in FEF.

Perception Space—The Final Frontier

Jakob von Uexkull coined the term Umwelt to describe the subjective world of animals. The world that animals perceive is not an objective, veridical representation of the physical world, he argued, but is instead a product of the particular sense organs that each species has acquired in its evolutionary history [1]. Many animals have sensory abilities that humans don't, such as a magnetic compass sense in birds [2] or sensitivity to electric fields in fish [3]. But even within sensory modalities shared by many animals, such as vision, hearing, and olfaction, there are strong differences between species. For example, bees, but not humans, can see UV light [4,5] and smell carbon dioxide [6], and bats can hear ultrasound [7]. But what exactly is the structure of the perceptual worlds proposed by von Uexkull? Can we draw them on paper in the form of maps, allowing us to visualize a particular animal's subjective view of the world? Will such maps allow us to predict the similarity of two stimuli (e.g., two colors or two scents) by inspecting the distance between the loci they produce in a perceptual space? Does understanding the metrics of such maps help us predict how stimulus mixtures will be perceived?

Application-driven design of auralization systems

Acoustical environmental simulation (auralization) involves rendering a binaural signal that articulates simultaneously the positional information of a sound source and the source’s acoustic and vibratory interaction with its environmental context. This places significant challenges on both the modeling and rendering components of such a system. Overcoming real-time limitations of processors can be accomplished by implementing rendering limits based on auditory threshold data for both early reflections and late reverberant energy. However, final assessment of system quality is dependent on the specific task or goal of the simulation. The use of auralization in accomplishing a telerobotic task requires head tracking and low latency, while environmental cues such as obstacles with acoustic reflections can be simplified and exaggerated beyond veridical representation. Contrasting this is the task of assessing speech intelligibility of an emergency public address system, or the quality of a space for musical performance, requiring a more accurate level of simulation of acoustical materials and sound-source characteristics. Modeling accuracy is complicated by such factors as the level of variance in the absorptive and diffusive properties of materials in terms of their real-world application. Assessment of auralization quality must therefore involve a best estimate of significant factors for a particular application.

Representational specificity of within-category phonetic variation in the mental lexicon

This study examines whether within-category variation in voice onset time (VOT) is encoded in long-term memory and affects subsequent word recognition, and whether these effects are modulated by the degree of lexical discriminability. Four long-term repetition-priming experiments were conducted using words containing word-initial voiceless stops varying in VOT. The magnitude of priming was compared between same and different VOT conditions in words with voiced counterparts (pat/bat) and words without voiced counterparts (cow/*gow), and in words with high-frequency counterparts (clue/glue) and words with low-frequency counterparts (cab/gab). If veridical representations of each episode are preserved in memory, variation in VOT should have demonstrable effects on the magnitude of priming. However, if within-category variation is discarded and form-based representations are abstract, variation in VOT should not mediate priming. Further, if lexical discriminability modulates the degree of encoding of within-category variation, words with counterparts and words with high-frequency counterparts should show larger specificity effects than words without counterparts and words with low-frequency counterparts. Implications of these results for the specificity and abstractness of phonetic representations in long-term memory will be discussed.

Representational specificity of within-category phonetic variation in the mental lexicon

This study examines (1) whether within-category phonetic variation in voice onset time (VOT) is encoded in long-term memory and has consequences for subsequent word recognition and, if so, (2) whether such effects are greater in words with voiced counterparts (pat/bat) than those without (cow/*gow), given that VOT information is more critical for lexical discrimination in the former. Two long-term repetition priming experiments were conducted using words containing word-initial voiceless stops varying in VOT. Reaction times to a lexical decision were compared between the same and different VOT conditions in words with or without voiced counterparts. If veridical representations of each episode are preserved in memory, variation in VOT should have demonstrable effects on the magnitude of priming. However, if within-category variation is discarded and form-based representations are abstract, the variation in VOT should not mediate priming. The implications of these results for the specificity and abstractness of phonetic representations in long-term memory will be discussed.

From the Inverted-U to the Extended-U: The Evolution of a Law of Psychology

The Yerkes-Dodson relationship is one of the oldest 'laws' behavioral research. It is used repeatedly as an explanation for stress effects on performance and is a fixture of undergraduate psychological texts. However, as is the case of most classics, it is more cited than read. In actuality, Yerkes and Dodson's report dealt with animal learning under states of compulsion and is only tangentially related to human performance in stress filled conditions. Our re-evaluation is motivated by two primary circumstances. The first is the evident failure of the unitary arousal notion, which has commonly been invoked as the causal source to explain the Yerkes-Dodson, inverted-U relationship. The second relates to criticisms of the curvilinear description itself and its interpretations, which we present here. Together, these concerns demand not simply a re-evaluation, but a replacement of this over-simplistic and fundamentally flawed proposition. In repealing this 'law,' we offer a more sophisticated and hopefully more veridical representation, which is given primarily in the following reprinted article of Hancock and Warm (1989). This approach posits an 'extended-U' description founded upon attention and adaptability as central mechanisms of response.