Perceptions Of Expectations Research Articles

All words are not created equal: Expectations about word length guide infant statistical learning

Infants have been described as ‘statistical learners’ capable of extracting structure (such as words) from patterned input (such as language). Here, we investigated whether prior knowledge influences how infants track transitional probabilities in word segmentation tasks. Are infants biased by prior experience when engaging in sequential statistical learning? In a laboratory simulation of learning across time, we exposed 9- and 10-month-old infants to a list of either disyllabic or trisyllabic nonsense words, followed by a pause-free speech stream composed of a different set of disyllabic or trisyllabic nonsense words. Listening times revealed successful segmentation of words from fluent speech only when words were uniformly disyllabic or trisyllabic throughout both phases of the experiment. Hearing trisyllabic words during the pre-exposure phase derailed infants’ abilities to segment speech into disyllabic words, and vice versa. We conclude that prior knowledge about word length equips infants with perceptual expectations that facilitate efficient processing of subsequent language input.

Reducing expectations: Is an extension of current boundary extension theories needed?

Boundary extension is a phenomenon in which people remember seeing more of a recently-viewed image than was actually shown. Typically, close-angle images produce greater amounts of extension than wide-angle images, however, images must be perceived as having a continuous, yet truncated, view of the world. Current theories of boundary extension suggest the phenomenon involves a source monitoring error between mental representations created by sensory information present in the image and representations containing amodal information based on perceptual expectations. If this is the case images/scenes with reduced expectations to amodally continue should not produce or minimally produce boundary extension. In the current study we tested this idea by removing a number of factors thought to contribute to amodal continuation including familiarity, texture gradients, and occlusion information. We did this by using 2-D abstract shapes on random-dot backgrounds where the backgrounds were either occluded by the border or not and where the objects occluded the random-dots or not. We found boundary extension occurred in all conditions created to minimize amodal continuation. These results suggest modification of current boundary extension theories may be necessary to incorporate the present findings.

The Second-Agent Effect: Communicative Gestures Increase the Likelihood of Perceiving a Second Agent

BackgroundBeyond providing cues about an agent's intention, communicative actions convey information about the presence of a second agent towards whom the action is directed (second-agent information). In two psychophysical studies we investigated whether the perceptual system makes use of this information to infer the presence of a second agent when dealing with impoverished and/or noisy sensory input.Methodology/Principal FindingsParticipants observed point-light displays of two agents (A and B) performing separate actions. In the Communicative condition, agent B's action was performed in response to a communicative gesture by agent A. In the Individual condition, agent A's communicative action was replaced with a non-communicative action. Participants performed a simultaneous masking yes-no task, in which they were asked to detect the presence of agent B. In Experiment 1, we investigated whether criterion c was lowered in the Communicative condition compared to the Individual condition, thus reflecting a variation in perceptual expectations. In Experiment 2, we manipulated the congruence between A's communicative gesture and B's response, to ascertain whether the lowering of c in the Communicative condition reflected a truly perceptual effect. Results demonstrate that information extracted from communicative gestures influences the concurrent processing of biological motion by prompting perception of a second agent (second-agent effect).Conclusions/SignificanceWe propose that this finding is best explained within a Bayesian framework, which gives a powerful rationale for the pervasive role of prior expectations in visual perception.

P16 Breaches of perceptual expectations yield caudate responses irrespective reward availability

P16 Breaches of perceptual expectations yield caudate responses irrespective reward availability

FMRI Repetition Suppression: Neuronal Adaptation or Stimulus Expectation?

Measurements of repetition suppression with functional magnetic resonance imaging (fMRI adaptation) have been used widely to probe neuronal population response properties in human cerebral cortex. fMRI adaptation techniques assume that fMRI repetition suppression reflects neuronal adaptation, an assumption that has been challenged on the basis of evidence that repetition-related response changes may reflect unrelated factors, such as attention and stimulus expectation. Specifically, Summerfield et al. (Summerfield C, Trittschuh EH, Monti JM, Mesulam MM, Egner T. 2008. Neural repetition suppression reflects fulfilled perceptual expectations. Nat Neurosci. 11:1004-1006) reported that the relative frequency of stimulus repetitions and non-repetitions influenced the magnitude of repetition suppression in the fusiform face area, suggesting that stimulus expectation accounted for most of the effect of repetition. We confirm that stimulus expectation can significantly influence fMRI repetition suppression throughout visual cortex and show that it occurs with long as well as short adaptation durations. However, the effect was attention dependent: When attention was diverted away from the stimuli, the effects of stimulus expectation completely disappeared. Nonetheless, robust and significant repetition suppression was still evident. These results suggest that fMRI repetition suppression reflects a combination of neuronal adaptation and attention-dependent expectation effects that can be experimentally dissociated. This implies that with an appropriate experimental design, fMRI adaptation can provide valid measures of neuronal adaptation and hence response specificity.

Modality-Specific Perceptual Expectations Selectively Modulate Baseline Activity in Auditory, Somatosensory, and Visual Cortices

Valid expectations are known to improve target detection, but the preparatory attentional mechanisms underlying this perceptual facilitation remain an open issue. Using functional magnetic resonance imaging, we show here that expecting auditory, tactile, or visual targets, in the absence of stimulation, selectively increased baseline activity in corresponding sensory cortices and decreased activity in irrelevant ones. Regardless of sensory modality, expectancy activated bilateral premotor and posterior parietal areas, supplementary motor area as well as right anterior insula and right middle frontal gyrus. The bilateral putamen was sensitive to the modality specificity of expectations during the unexpected omission of targets. Thus, across modalities, detection improvement arising from selectively directing attention to a sensory modality appears mediated through transient changes in pretarget activity. This flexible advance modulation of baseline activity in sensory cortices resolves ambiguities among previous studies unable to discriminate modality-specific preparatory activity from attentional modulation of stimulus processing. Our results agree with predictive-coding models, which suggest that these expectancy-related changes reflect top-down biases--presumably originating from the observed supramodal frontoparietal network--that modulate signal-detection sensitivity by differentially modifying background activity (i.e., noise level) in different input channels. The putamen appears to code omission-related Bayesian "surprise" that depends on the specificity of predictions.

Expectations Change the Signatures and Timing of Electrophysiological Correlates of Perceptual Awareness

Previous experience allows the brain to predict what comes next. How these expectations affect conscious experience is poorly understood. In particular, it is unknown whether and when expectations interact with sensory evidence in granting access to conscious perception, and how this is reflected electrophysiologically. Here, we parametrically manipulate sensory evidence and expectations while measuring event-related potentials in human subjects to assess the time course of evoked responses that correlate with subjective visibility, the properties of the stimuli, and/or perceptual expectations. We found that expectations lower the threshold of conscious perception and reduce the latency of neuronal signatures differentiating seen and unseen stimuli. Without expectations, this differentiation occurs ∼300 ms and with expectations ∼200 ms after stimulus in occipitoparietal sensors. The amplitude of this differentiating response component (P2) decreases as visibility increases, regardless of whether this increase is attributable to enhanced sensory evidence and/or the gradual buildup of perceptual expectations. Importantly, at matched performance levels, responses to seen and unseen stimuli differed regardless of the physical stimulus properties. These findings indicate that the latency of the neuronal correlates of access to consciousness depend on whether access is driven by stimulus saliency or by a combination of expectations and sensory evidence.

The Role of Perceptual Expectation on Repetition Suppression: A Quest to Dissect the Differential Contribution of Probability of Occurrence and Event Predictability

The Role of Perceptual Expectation on Repetition Suppression: A Quest to Dissect the Differential Contribution of Probability of Occurrence and Event Predictability

Expectation and attention in visual cognition: neural and computational approaches.

Event Abstract Back to Event Expectation and attention in visual cognition: neural and computational approaches. Christopher Summerfield1* 1 University of Oxford, United Kingdom A rich literature has explored how top-down anticipatory biases help resolve competition among visual representations. In many studies, attention is biased via probabilistic cues signaling what is likely to occur, or at which location. However, this class of paradigm confounds the relevance of a feature or location for behaviour, and the conditional probability that a specific event will occur. Outside of the laboratory, these two sources of information, stimulus relevance (here, ‘attention’) and stimulus probability (here, ‘expectation’), do not always vary together - for example, statistical regularities in the environment are learned even when they are task-irrelevant. We will describe empirical and theoretical work aimed at dissociating the influences of expectation and attention on visual cognition. Speaker 1 (Summerfield) will describe novel psychophysical methods revealing dissociable effects of signal relevance and signal probability on detection sensitivity, and propose a computational model to account for these effects. Speaker 2 (de Lange) will describe retinotopically mapped blood-oxygen level dependent (BOLD) signals in the visual cortex that respond to expectation and attention. Speaker 3 (Turk-Browne) will describe prospective BOLD signals in the extrastriate visual cortex that encode the conditional probability of occurrence of a stimulus in the absence of attention. Speaker 4 (Seriès) will propose a computational model in which statistical learning promotes perceptual expectations, and show that this model can account for well-described biases in discrimination tasks. Collectively, this work suggests that attention and expectation may modulate information processing in the visual system, and it neural consequences, in a dissociable fashion. Keywords: BOLD signal, visual cognition Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Introduction Topic: Symposium 6: Expectation and attention in visual cognition: neural and computational approaches Citation: Summerfield C (2011). Expectation and attention in visual cognition: neural and computational approaches.. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00036 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 Nov 2011; Published Online: 15 Nov 2011. * Correspondence: Dr. Christopher Summerfield, University of Oxford, Oxford, United Kingdom, christopher.summerfield@psy.ox.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Christopher Summerfield Google Christopher Summerfield Google Scholar Christopher Summerfield PubMed Christopher Summerfield Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Expectation and Surprise Determine Neural Population Responses in the Ventral Visual Stream

Visual cortex is traditionally viewed as a hierarchy of neural feature detectors, with neural population responses being driven by bottom-up stimulus features. Conversely, "predictive coding" models propose that each stage of the visual hierarchy harbors two computationally distinct classes of processing unit: representational units that encode the conditional probability of a stimulus and provide predictions to the next lower level; and error units that encode the mismatch between predictions and bottom-up evidence, and forward prediction error to the next higher level. Predictive coding therefore suggests that neural population responses in category-selective visual regions, like the fusiform face area (FFA), reflect a summation of activity related to prediction ("face expectation") and prediction error ("face surprise"), rather than a homogenous feature detection response. We tested the rival hypotheses of the feature detection and predictive coding models by collecting functional magnetic resonance imaging data from the FFA while independently varying both stimulus features (faces vs houses) and subjects' perceptual expectations regarding those features (low vs medium vs high face expectation). The effects of stimulus and expectation factors interacted, whereby FFA activity elicited by face and house stimuli was indistinguishable under high face expectation and maximally differentiated under low face expectation. Using computational modeling, we show that these data can be explained by predictive coding but not by feature detection models, even when the latter are augmented with attentional mechanisms. Thus, population responses in the ventral visual stream appear to be determined by feature expectation and surprise rather than by stimulus features per se.

Stimulus Repetition Probability Does Not Affect Repetition Suppression in Macaque Inferior Temporal Cortex

Recent human functional magnetic resonance imaging studies (Summerfield C, Trittschuh EH, Monti JM, Mesulam MM, Egner T. 2008. Neural repetition suppression reflects fulfilled perceptual expectations. Nat Neurosci. 11:1004-1006.) showed that adaptation or repetition suppression is affected by contextual factors related to perceptual expectations, suggesting that adaptation results from a fulfillment of perceptual expectation or a reduction in prediction error. This view contrasts with the bottom-up fatigue or sharpening mechanisms of adaptation proposed in single-cell studies. We examined whether stimulus repetition probability affects adaptation of spiking activity and local field potentials (LFPs) in macaque inferior temporal (IT) cortex, using a protocol similar to that of Summerfield et al. Monkeys were exposed to 2 randomly interleaved trials, each consisting of either 2 identical (rep trial) or 2 different stimuli (alt trial). Trials were presented in repetition (rep) blocks consisting of 75% of rep trials and 25% of alt trials or in alternation (alt) blocks having opposite repetition probabilities. For both spiking and LFP activities, the stimulus-selective adaptation did not differ significantly between rep and alt blocks. The number of preceding rep or alt trials and the trial position within a block did not affect adaptation. This absence of any effect of stimulus repetition probability on adaptation suggests that adaptation in IT is not caused by contextual factors related to perceptual expectation.

Auditory expectations for newly acquired structures

Our study investigated whether newly acquired auditory structure knowledge allows listeners to develop perceptual expectations for future events. For that aim, we introduced a new experimental approach that combines implicit learning and priming paradigms. Participants were first exposed to structured tone sequences without being told about the underlying artificial grammar. They then made speeded judgements on a perceptual feature of target tones in new sequences (i.e., in-tune/out-of-tune judgements). The target tones respected or violated the structure of the artificial grammar and were thus supposed to be expected or unexpected. In this priming task, grammatical tones were processed faster and more accurately than ungrammatical ones. This processing advantage was observed for an experimental group performing a memory task during the exposure phase, but was not observed for a control group, which was lacking the exposure phase (Experiment 1). It persisted when participants realized an in-tune/out-of-tune detection task during exposure (Experiment 2). This finding suggests that the acquisition of new structure knowledge not only influences grammaticality judgements on entire sequences (as previously shown in implicit learning research), but allows developing perceptual expectations that influence single event processing. It further promotes the priming paradigm as an implicit access to acquired artificial structure knowledge.

Expecting the unexpected: Dissociating visual similarity from perceptual expectation in neural repetition attenuation

Expecting the unexpected: Dissociating visual similarity from perceptual expectation in neural repetition attenuation

Perceptual expectations, attention, and speech recognition.

Research has demonstrated substantial plasticity in the adult speech perceiver. When listeners receive feedback about the classification of a speech signal, this feedback can shape attention affecting phoneme perception. This demonstrates that it is possible to shape perceptual attention prospectively changing subsequent speech perception. These changes can also reduce the cognitive load of speech perception. The effect of expectations on speech perception has been reported for a wide range of studies from sinewave speech perception to phonetic categorization and effects of talker variability. Neural changes occurring during learning and the neural effects of expectations both appear to involve regions of motor cortex implicated in speech production. These neural changes suggest a model of speech perception similar to analysis-by-synthesis in which sensory processes are tuned by activity within the speech motor system. Although such sensory-motor interactions have been implicated in speech perception due to coarticulation and the encoding of speech into sound, the role of expectations in speech perception may extend beyond segmental perception. We consider evidence that the interpretation of prosodic signals also depends on perceptual expectations, suggesting that the role of expectations may be to constrain recognition given the many-to-many relationship that holds broadly in speech.

PHENOMENOLOGY AND INTERPRETATION BEYOND THE FLESH

This article explores the ethical questions surrounding the phenomenological approach to interpretation in art history. It addresses contemporary art, from postminimalist sculpture to installation. Although the risk of phenomenology is that it merely confirms and reproduces the viewer's perceptual expectations, in fact, on a deeper level, the notion of the ontological intertwining of the viewer and the artwork demands a receptive stance in the face of art. Through an investigation of the notions of embodiment, intentionality, and mode of confrontation, I suggest that phenomenology not only mediates a trenchant understanding of the perceptual experience of the artwork, it is predicated on an acknowledgement of the artwork's alterity from interpretation. In this way, it invites a consideration of the linguistic malleability implicit in the fleshly chiasm that binds the viewer to the artwork.

Neural basis of perceptual expectations: insights from transient dynamics of attractor neural networks

Sensory information from the external world is intrinsically ambiguous, necessitating prior experience as a constraint on perception to parse stimuli into well-defined categories. Priming, which have been used vastly to study such perceptual influences, is the phenomenon where the perception of a given stimulus, or the prime, affects the perception of a succeeding stimulus, or the target, even when the target is presented after a long delay or the prime is not explicitly perceived [1]. Using classical priming paradigms, it is observed that brief exposure to a stimulus – ranging from tens to hundreds of milliseconds – biases subjects to perceive the following stimuli either as dissimilar (adaptation aftereffects) or more similar (priming) to the priming stimuli [2,3]. Thus, in a categorization task, the category boundary may move towards or away from the prime. The duration of the prime and the prime-target asynchrony, as well as the type of intervening mask, affect both the strength and the direction of the effect [2,4]. Current evidence has led to the suggestion that a particular type of the observed priming effect may be primarily due to the conflicting acts of lingering activation from the prime and accumulating depletion of synaptic resources [5]. Some other studies looked at the interaction between local shunting adaptation and a near-threshold neural baseline [6]. This neural model explains the observed behavior, without invoking any high-level decision making or memory process. However, it has been shown that also high-level, complex processes such as face perception are subject to aftereffects, namely rate firing adaptation. In spite of a large body of empirical data on various behavioral outcomes in such experiments, we still lack an explanatory model capable of predicting the crossover from adaptation aftereffect to priming, as emerging in a generic cortical network. We have developed an analytical approach to study the transient dynamics of networks of threshold-linear model neurons that include, as a necessary ingredient of the relevant computational mechanism, a simple feature of pyramidal cell biophysics: firing rate adaptation. The analysis yields the attractor states of the network and the full spectrum of time constants of the transients associated with different steady states. Studying these transients, in the response to external inputs that are morphed between two stored patterns, and affected by previous activity of the network, could shed light on the possible contribution of attractor dynamics to perceptual boundary shifts. The preliminary results show that firing rate adaptation plays the main role to produce adaptation aftereffects in our network, without which one only observes priming effects, if any. The relative duration of target length and adaptation time scale is one of the crucial terms determining the dynamics. The strength of recurrent connection with respect to feedforward inputs is another relevant parameter.

LARGE-SCALE CORTICAL NETWORK COORDINATION: A PROPOSAL FOR THE NEURAL SUBSTRATE OF EXPECTANCY

Optimal human behavior depends on the expectancy of future events based on perceptual analysis of an individual's present situation using knowledge gained from past experience. This article explores the proposition that the neural processes underlying perceptual analysis, knowledge retrieval, and expectancy are all integrated through the coordination of large-scale networks of the cerebral cortex. It is proposed that expectancy is created when local networks expressing knowledge of the likely future events associated with an individual's present situation are coordinated as part of large-scale networks expressing the totality of knowledge relations concerning the situation.

Violation of Expectation: Neural Correlates Reflect Bases of Prediction

Setting perceptual expectations can be based on different sources of information that determine which functional networks will be involved in implementing preparatory top-down influences and dealing with situations in which expectations are violated. The goal of the present study was to investigate and directly compare brain activations triggered by violating expectations within two different task contexts. In the serial prediction task, participants monitored ordered perceptual sequences for predefined sequential deviants. In contrast, the target detection task entailed a presentation of stimuli which had to be monitored for predefined nonsequential deviants. Detection of sequential deviants triggered an increase of activity in premotor and cerebellar components of the "standard" sequencing network and activations in additional frontal areas initially not involved in sequencing. This pattern of activity reflects the detection of a mismatch between the expected and presented stimuli, updating of the underlying sequence representation (i.e., forward model), and elaboration of the violation. In contrast, target detection elicited activations in posterior temporal and parietal areas, reflecting an increase in perceptual processing evoked by the nonsequential deviant. The obtained results suggest that distinct functional networks involved in detecting deviants in different contexts reflect the origin and the nature of expectations being violated.

Semantic Expectations Can Induce False Perceptions in Hallucination-Prone Individuals

Recently, it has been proposed that exaggerated top-down processing may generate spontaneous perceptual output, and that this may constitute a cognitive predisposition toward hallucinations. In this experiment, we investigated whether hallucination proneness would be associated with increased auditory-verbal perceptual expectations, and at which processing level this occurs. From 351 undergraduate students screened for hallucination proneness, using the Launay-Slade Hallucination Scale (LSHS), 42 subjects were recruited for participation. Two word recognition tasks were administered, in which top-down influences on perception were manipulated through sentence context (semantic task) or auditory imagery (phonological task). Results revealed that LSHS scores were correlated with the number of semantically primed errors. Subjects with higher levels of hallucination proneness were more likely to report hearing a word that fits the sentence context, when it was not actually presented. This effect remained significant after controlling for general performance on the task. In contrast, hallucination proneness was not associated with phonologically primed errors. We conclude that aberrant top-down processing, particularly in the form of strong semantic expectations, may contribute to the experience of auditory-verbal hallucinations.

Violation of expectation: Neural correlates reflect bases of prediction

Setting perceptual expectations can be based on different sources of information which determine the functional networks involved in implementing preparatory top-down influences and dealing with situations in which expectations are violated. The present study addressed the process of forming and violating expectations based on information of different origin, type and specificity. In the serial prediction task participants monitored ordered perceptual sequences for predefined sequential deviants, while the target detection task entailed a presentation of stimuli which had to be monitored for predefined non-sequential deviants.