Optimal combination of environmental cues and path integration during navigation

Navigation is influenced by body-based self-motion cues that are integrated over time, in a process known as path integration, as well as by environmental cues such as landmarks and room shape. In two experiments we explored whether humans combine path integration and environmental cues (Exp. 1: room shape; Exp. 2: room shape, single landmark, and multiple landmarks) to reduce response variability when returning to a previously visited location. Participants walked an outbound path in an immersive virtual environment before attempting to return to the path origin. Path integration and an environmental cue were both available during the outbound path, but experimental manipulations created single- and dual-cue conditions during the return path. The response variance when returning to the path origin was reduced when both cues were available, consistent with optimal integration predicted on the basis of Bayesian principles. The findings indicate that humans optimally integrate multiple spatial cues during navigation. Additionally, a large (but not a small) cue conflict caused participants to assign a higher weight to path integration than to environmental cues, despite the relatively greater precision afforded by the environmental cues.     

Multiple cue use and integration in pigeons (<Emphasis Type="Italic">Columba livia</Emphasis>)

Encoding multiple cues can improve the accuracy and reliability of navigation and goal localization. Problems may arise, however, if one cue is displaced and provides information which conflicts with other cues. Here we investigated how pigeons cope with cue conflict by training them to locate a goal relative to two landmarks and then varying the amount of conflict between the landmarks. When the amount of conflict was small, pigeons tended to integrate both cues in their search patterns. When the amount of conflict was large, however, pigeons used information from both cues independently. This context-dependent strategy for resolving spatial cue conflict agrees with Bayes optimal calculations for using information from multiple sources.     

Information integration in judgements of time to contact

Time to contact (TTC) is specified optically by tau, and studies suggest that observers are sensitive to this information. However, TTC judgements also are influenced by other sources of information, including pictorial depth cues. Therefore, it is useful to identify these sources of information and to determine whether and how their effects combine when multiple sources are available. We evaluated the effect of five depth cues on TTC judgements. Results indicate that relative size, height in field, occlusion, and motion parallax influence TTC judgements. When multiple cues are available, an integration (rather than selection) strategy is used. Finally, the combined effects of multiple cues are not always consistent with a strict additive model and may be task dependent.     

Inhibitory interaction: the effects of multiple non-predictive visual cues

When the interval between a non-predictive cue and a target appearing at the same spatial location is longer than about 200 ms, target performance is typically poorer than when the cue and target appear at different locations. Recent studies have shown that this effect, known as inhibition of return (IOR), can occur at multiple cued locations, and is enhanced when multiple cues are presented at the same spatial location. However, little is known about how the magnitude of IOR at one spatial location is influenced by a subsequent or preceding cue presented at a different spatial location. We investigated this issue by presenting single or multiple cues at varying inter-cue intervals prior to target onset. Results suggest that the magnitude of IOR at a given location is influenced by the presentation of a preceding cue, but that once IOR occurs, it is unaffected by the presentation of a subsequent cue.     

Cue combination in human spatial navigation

This project investigated the ways in which visual cues and bodily cues from self-motion are combined in spatial navigation. Participants completed a homing task in an immersive virtual environment. In Experiments 1A and 1B, the reliability of visual cues and self-motion cues was manipulated independently and within-participants. Results showed that participants weighted visual cues and self-motion cues based on their relative reliability and integrated these two cue types optimally or near-optimally according to Bayesian principles under most conditions. In Experiment 2, the stability of visual cues was manipulated across trials. Results indicated that cue instability affected cue weights indirectly by influencing cue reliability. Experiment 3 was designed to mislead participants about cue reliability by providing distorted feedback on the accuracy of their performance. Participants received feedback that their performance with visual cues was better and that their performance with self-motion cues was worse than it actually was or received the inverse feedback. Positive feedback on the accuracy of performance with a given cue improved the relative precision of performance with that cue. Bayesian principles still held for the most part. Experiment 4 examined the relations among the variability of performance, rated confidence in performance, cue weights, and spatial abilities. Participants took part in the homing task over two days and rated confidence in their performance after every trial. Cue relative confidence and cue relative reliability had unique contributions to observed cue weights. The variability of performance was less stable than rated confidence over time. Participants with higher mental rotation scores performed relatively better with self-motion cues than visual cues. Across all four experiments, consistent correlations were found between observed weights assigned to cues and relative reliability of cues, demonstrating that the cue-weighting process followed Bayesian principles. Results also pointed to the important role of subjective evaluation of performance in the cue-weighting process and led to a new conceptualization of cue reliability in human spatial navigation.     

Vestibular stimulation affects optic-flow sensitivity

Typically, multiple cues can be used to generate a particular percept. Our area of interest is the extent to which humans are able to synergistically combine cues that are generated when moving through an environment. For example, movement through the environment leads to both visual (optic-flow) and vestibular stimulation, and studies have shown that non-human primates are able to combine these cues to generate a more accurate perception of heading than can be obtained with either cue in isolation. Here we investigate whether humans show a similar ability to synergistically combine optic-flow and vestibular cues. This was achieved by determining the sensitivity to optic-flow stimuli while physically moving the observer, and hence producing a vestibular signal, that was either consistent with the optic-flow signal, eg a radially expanding pattern coupled with forward motion, or inconsistent with it, eg a radially expanding pattern with backward motion. Results indicate that humans are more sensitive to motion-in-depth optic-flow stimuli when they are combined with complementary vestibular signals than when they are combined with conflicting vestibular signals. These results indicate that in humans, like in nonhuman primates, there is perceptual integration of visual and vestibular signals.     

Sense of agency in health and disease: a review of cue integration approaches

Sense of agency (SoA) is a compelling but fragile experience that is augmented or attenuated by internal signals and by external cues. A disruption in SoA may characterise individual symptoms of mental illness such as delusions of control. Indeed, it has been argued that generic SoA disturbances may lie at the heart of delusions and hallucinations that characterise schizophrenia. A clearer understanding of how sensorimotor, perceptual and environmental cues complement, or compete with, each other in engendering SoA may prove valuable in deepening our understanding the agency disruptions that characterise certain focal neurological disorders and mental illnesses. Here we examine the integration of SoA cues in health and illness, describing a simple framework of this integration based on Bayesian principles. We extend this to consider how alterations in cue integration may lead to aberrant experiences of agency.     

Cue Combinatorics in Memory Retrieval for Anaphora

Many studies have shown that memory retrieval for real‐time language processing relies on a cue‐based access mechanism, which allows the cues available at the retrieval site to directly access the target representation in memory. An open question is how different types of cues are combined at retrieval to create a single retrieval probe (“cue combinatorics”). This study addresses this question by testing whether retrieval for antecedent‐reflexive dependencies combines cues in a linear (i.e., additive) or nonlinear (i.e., multiplicative) fashion. Results from computational simulations and a reading time experiment show that target items that match all the cues of the reflexive are favored more than target items that mismatch these cues, and that different degrees of mismatches slow reading times in comparable amounts. This profile is consistent with the predictions of a nonlinear cue combination and provides evidence against models in which all cues combine in a linear fashion. A follow‐up set of simulations shows that a nonlinear rule also captures previous demonstrations of interference from nontarget items during retrieval for reflexive licensing. Taken together, these results shed new light on how different types of cues combine at the retrieval site and reveal how the method of cue combination impacts the accessibility of linguistic information in memory.     

Crossmodal integration in the identification of consonant segments

Although speechreading can be facilitated by auditory or tactile supplements, the process that integrates cues across modalities is not well understood. This paper describes two “optimal processing” models for the types of integration that can be used in speechreading consonant segments and compares their predictions with those of the Fuzzy Logical Model of Perception (FLMP, Massaro, 1987). In “pre-labelling” integration, continuous sensory data is combined across modalities before response labels are assigned. In “post-labelling” integration, the responses that would be made under unimodal conditions are combined, and a joint response is derived from the pair. To describe pre-labelling integration, confusion matrices are characterized by a multidimensional decision model that allows performance to be described by a subject's sensitivity and bias in using continuous-valued cues. The cue space is characterized by the locations of stimulus and response centres. The distance between a pair of stimulus centres determines how well two stimuli can be distinguished in a given experiment. In the multimodal case, the cue space is assumed to be the product space of the cue spaces corresponding to the stimulation modes. Measurements of multimodal accuracy in five modern studies of consonant identification are more consistent with the predictions of the pre-labelling integration model than the FLMP or the post-labelling model.     

Combined expectancy effects are modulated by the relation between expectancy cues

Studies of combined expectancies have shown that spatial cueing effects are reduced on trials on which participants have to respond with an unexpected motor response. In the first two experiments the range of reduced expectancy effects is examined. Advance knowledge of the likely response was combined in a trial-by-trial procedure with modality cueing, object cueing, and task cueing. Effects of modality cueing were reduced on trials on which the target requested an unexpected response. However, effects of object cueing as well as effects of task cueing were unaffected by response cueing. Comparing experiments revealed that different types of cues were used in different experiments. To test the effect of type of cue on the interaction of expectancies the third experiment combined spatial cueing with response cueing. When integrated cues were used that cued the likely target location by an arrow and the likely response by an arrow too, spatial cueing effects were reduced on trials with unexpected responses. However, spatial cueing effects remained unaffected by response cueing when separated cues were used consisting in a word cueing the response and an arrow cueing target location. An account for the modulation of combined expectancies by the relation between cues is suggested in terms of the adjusted expectancy model.     

Laying it on thin: analogical cue frequency in the manipulation of choice

Persuasive analogies consist of linguistic cues that invite audiences to represent a problem in terms of an analog and to make choices compatible with this manipulated representation. The authors explore how the frequency of linguistic cues moderates analogical bias in choice behavior. Participants read versions of a managerial decision scenario differing in the number of sports (e.g., game plan) or family (e.g., parent company) idioms used to describe situational attributes and then chose between analogically consistent and inconsistent response options. Analogies consisting of an intermediate number of cues elicited higher rates of analogically consistent responding than those of higher and lower cue frequency. When explaining their responses, participants referred to the sports or family analogies most often to rationalize rejecting the analogically consistent response option after reading high cue frequency versions. These findings indicate that there are lower and upper boundaries to a persuasive analogy's optimal cue frequency.     

Variation in cue duration reveals top-down modulation of involuntary orienting to uninformative symbolic cues

This article reports three experiments in which the effects of cue duration on involuntary orienting to uninformative symbolic cues (arrows presented at fixation) were investigated. Experiment 1 showed that symbolic cues had less effect on involuntary orienting when they were presented for only 25 msec than when they were presented for 200 msec across a range of stimulus onset asynchronies. Experiment 2 suggested that the effect of cue duration on involuntary orienting was due primarily to top-down strategic factors, rather than to bottom-up stimulus factors, and Experiment 3 suggested that these strategic factors may involve differences in how the cue is processed. Altogether, the present findings are important because they emphasize the distinction between cue processing and the putative involuntary orienting that results from such processing in the symbolic-cuing paradigm. In so doing, the present results help resolve discrepant findings that have been reported across previous studies.     

Perceptual equivalence of two acoustic cues for stop-consonant manner

The first experiment examined the effects of orthogonal variation in two acoustic cues that are both produced by the articulation of a stop consonant. One component of the articulation produces a temporal cue, the other a spectral cue. In a phonetic identification task, these quite different cues were found to engage in a trading relation: One cue could, within limits, substitute for the other. In a second experiment, the perceptual equivalence implied by that trading relation was put to a stricter test. If the cues are truly equivalent in perception, then they should have their effects on the same perceptual dimension. That being so, it should be possible to combine them in such a way that, working at cross purposes in the perceptual domain, they effectively cancel each other. Pairs of patterns so produced should, then, be harder to discriminate than pairs produced by either cue alone, and still harder than those produced when the (same) two cues are combined in the opposite way and so cooperate. That expectation was confirmed. We suggest that the equivalence thus demonstrated comes about because the two cues are processed by a system specialized to take account of their common origin in speech production. So interpreted, the equivalence may be viewed as an instance of distinctively phonetic perception.     

Attentional shifts to emotionally charged cues: Behavioural and erp data

Abstract

When information activated in memory involves emotional associations, the ability to shift attention away from an emotional cue is impaired compared to an emotionally neutral cue. The purpose of the present study was to investigate how emotional stimuli modulate attentional processes, and how this is reflected in localised brain electrical activity. Eight emotion and eight neutral words served as cues in a covert attention spatial orienting task. The cues were either valid or invalid indicators of which hemifield the target would be presented to. In the remaining trials, no cue was presented prior to the target. Twenty subjects were instructed to manually respond to the target as fast as possible. Event-related potentials (ERPs) showed an enhanced P3 component to the emotion words. The ERPs to the target showed enhanced P1 and P3 components on invalid trials, with emotional cues. There were faster reaction times (RTs) to validly cued targets, but only when the emotion words served as cues. The results demonstrated that the emotional cues elicited sustained focused attention, facilitating an engage mechanism of spatial orienting.     

Flexible cue use in food-caching birds

An animal’s memory may be limited in capacity, which may result in competition among available memory cues. If such competition exists, natural selection may favor prioritization of different memory cues based on cue reliability and on associated differences in the environment and life history. Food-caching birds store numerous food items and appear to rely on memory to retrieve caches. Previous studies suggested that caching species should always prioritize spatial cues over non-spatial cues when both are available, because non-spatial cues may be unreliable in a changing environment; however, it remains unclear whether non-spatial cues should always be ignored when spatial cues are available. We tested whether mountain chickadees (Poecile gambeli), a food-caching species, prioritize memory for spatial cues over color cues when relocating previously found food in an associative learning task. In training trials, birds were exposed to food in a feeder where both spatial location and color were associated. During subsequent unrewarded test trials, color was dissociated from spatial location. Chickadees showed a significant pattern of inspecting feeders associated with correct color first, prior to visiting correct spatial locations. Our findings argue against the hypothesis that the memory of spatial cues should always take priority over any non-spatial cues, including color cues, in food-caching species, because in our experiment mountain chickadees chose color over spatial cues. Our results thus suggest that caching species may be more flexible in cue use than previously thought, possibly dependent upon the environment and complexity of available cues.     

眼睛注视线索提示效应: 内源性注意还是外源性注意?

采用改进的Posner视-空间线索提示范式, 对眼睛注视线索提示效应(eyes gaze cueing effect)的加工机制进行了探讨。实验一考察注视提示线索对空间Stroop效应的影响; 实验二考察注视提示线索对特征抽取和特征整合的影响。实验结果显示: 注视线索提示有效时的空间Stroop效应显著大于提示无效的情景; 在单一特征搜索与特征联合搜索任务中, 注视线索提示效应无差别。这说明, 注视线索通过在头脑里形成空间方位表征诱导注意转移; 注视线索通过影响特征抽取、而非特征整合阶段, 对客体加工产生易化。本研究支持注视线索提示效应属于内源性注意的观点。     

Test of a distributional theory of intuitive numerical prediction

This paper investigates models that describe how subjects combine uncertain information to arrive at an intuitive prediction of a criterion. Subjects were trained, with feedback, to predict a numerical criterion from each of three single cues. Then they were asked to predict the criterion, without feedback, either from pairs of cues or from single cues. Their predictions were not consistent with a relative weight averaging model, since pairs of cues did not combine additively. Instead, the effect of a cue was inversely proportional to the standard deviation of the criterion at each level of the cue. Subjects appeared to apply greater weight to cue levels with smaller variance, i.e., those cue levels that were more valid. The data could be described by a distributional theory referred to as the equal probability model. For the present experiment, this model implies that the criterion means associated with the levels of each cue are weighted by the reciprocals of the standard deviations and then averaged. Relations between the equal probability model and other models of impression formation are discussed.     

Cue integration with categories: Weighting acoustic cues in speech using unsupervised learning and distributional statistics

During speech perception, listeners make judgments about the phonological category of sounds by taking advantage of multiple acoustic cues for each phonological contrast. Perceptual experiments have shown that listeners weight these cues differently. How do listeners weight and combine acoustic cues to arrive at an overall estimate of the category for a speech sound? Here, we present several simulations using a mixture of Gaussians models that learn cue weights and combine cues on the basis of their distributional statistics. We show that a cue‐weighting metric in which cues receive weight as a function of their reliability at distinguishing phonological categories provides a good fit to the perceptual data obtained from human listeners, but only when these weights emerge through the dynamics of learning. These results suggest that cue weights can be readily extracted from the speech signal through unsupervised learning processes.     

Evidence that blatant versus subtle stereotype threat cues impact performance through dual processes

An experiment tested three competing hypotheses for how blatant and subtle stereotype threat cues influence the performance of female sports participants on a golf-putting task. A “predominant” model predicts that blatant threat cues have a more negative effect on performance than subtle threat cues, whereas an “additive” model predicts that both cues combine to have a greater negative effect than either threat cue alone. However, a “dual process” model predicts that each threat cue has an independent negative influence through separate mechanisms. To test these predictions, we varied the presence of blatant (e.g., the task frame) and subtle cues (e.g., the gender of the experimenter) for negative stereotypes about female athletes, and then measured both the number of strokes required to finish the course and accuracy on the last putt of each hole. The results supported the dual process model prediction: females required more strokes to finish the golf task when it was framed as measuring gender differences compared to racial differences in athletic ability, and females performed less accurately on the last putt of each hole in the presence of a male versus a female experimenter. The discussion focuses on how the presence of multiple stereotype threat cues can induce independent mechanisms that may have separate but simultaneously deleterious effects on performance.     

Sensory mediation of stimulus-driven attentional capture in multiple-cue displays

Three location-cuing experiments were conducted in order to examine the stimulus-driven control of attentional capture in multiple-cue displays. These displays consisted of one to four simultaneously presented direct location cues. The results indicated that direct location cuing can produce cue effects that are mediated, in part, by nonattentional processing that occurs simultaneously at multiple locations. When single cues were presented in isolation, however, the resulting cue effect appeared to be due to a combination of sensory processing and attentional capture by the cue. This suggests that the faster responses produced by direct cues may be associated with two different components: an attention-related component that can be modulated by goal-driven factors and a nonattentional component that occurs in parallel at multiple direct-cue locations and is minimally affected by goal-driven factors.