Visual direction constancy across eyeblinks

When a visual target is displaced during a saccade, the perception of its displacement is suppressed. Its movement can usually only be detected if the displacement is quite large. This suppression can be eliminated by introducing a short blank period after the saccade and before the target reappears in a new location. This has been termed the blanking effect and has been attributed to the use of otherwise ignored extraretinal information. We examined whether similar effects occur with eyeblinks and other visual distractions. We found that suppression of displacement perception can also occur due to a blink (both immediately prior to the blink and during the blink), and that introducing a blank period after a blink reduces the displacement suppression in much the same way as after a saccade. The blanking effect does not occur when other visual distractions are used. This provides further support for the conclusion that the blanking effect arises from extraretinal signals about eye position.     

Some recent studies on the extraretinal contribution to distance perception

Some recent studies on the extraretinal contribution to distance perception are reviewed. These experiments demonstrate that vergence can provide reliable information for judgments on the distance of proximal targets in the absence of all other cues. We argue that, although vergence is an unreliable cue at large fixation distances and is subject to a strong contraction bias when studied in isolation, these facts do not imply a minor role for vergence in near-space perception. When additional depth and distance cues are added, the contribution of vergence information becomes more complicated. We present results which indicate that the different cues to depth and distance are combined in a manner that can result in unexpected distortions of visual space. A simple heuristic model which can produce the observed distortions is outlined.     

Morphological constraints in children’s spoken language comprehension: A visual world study of plurals inside compounds in English

Many previous studies have shown that the human language processor is capable of rapidly integrating information from different sources during reading or listening. Yet, little is known about how this ability develops from child to adulthood. To gain insight into how children (in comparison to adults) handle different kinds of linguistic information during on-line language comprehension, the current study investigates a well-known morphological phenomenon that is subject to both structural and semantic constraints, the plurals-in-compounds effect, i.e. the dislike of plural (specifically regular plural) modifiers inside compounds (e.g. rats eater). We examined 96 seven-to-twelve-year-old children and a control group of 32 adults measuring their eye-gaze changes in response to compound-internal plural and singular forms. Our results indicate that children rely more upon structural properties of language (in the present case, morphological cues) early in development and that the ability to efficiently integrate information from multiple sources takes time for children to reach adult-like levels.     

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.     

Kinaesthesis: Its measurement, training and relationship to motor control

This paper reviews studies which demonstrate the importance of kinaesthesis in the acquisition and performance of motor skills. A method of measuring kinaesthetic sensitivity in children and adults (recently developed) is briefly described. Developmental trends in kinaesthetic perception are discussed and large individual differences found within age groups. It was shown that kinaesthetically undeveloped children can be trained to perceive and memorize kinaesthetic information with greatly improved accuracy. Furthermore perceptual training facilitates the performance of a drawing skill. On the basis of these results an argument is made for the importance of kinaesthesis in skilled motor behaviour.     

Ipsilateral eye contributions to online visuomotor control of right upper-limb movements

A limb’s initial position is often biased to the right of the midline during activities of daily living. Given this specific initial limb position, visual cues of the limb become first available to the ipsilateral eye relative to the contralateral eye. The current study investigated online control of the dominant limb as a function of having visual cues available to the ipsilateral or contralateral eye, in relation to the initial start position of the limb. Participants began each trial with their right limb on a home position to the left or right of the midline. After movement onset, a brief visual sample was provided to the ipsilateral or contralateral eye. On one third of the trials, an imperceptible 3 cm target jump was introduced. If visual information from the eye ipsilateral to the limb is preferentially used to control ongoing movements of the dominant limb, corrections for the target jump should be observed when movements began from the right of the body’s midline and vision was available to the ipsilateral eye. As expected, limb trajectory corrections for the target jump were only observed when participants started from the right home position and visual information was provided to the ipsilateral eye. We purport that such visuomotor asymmetry specialization emerges via neurophysiological developments, which may arise from naturalistic and probabilistic limb trajectory asymmetries.     

Object recognition is mediated by extraretinal information

Many previous studies of object recognition have found view-dependent recognition performance when view changes are produced by rotating objects relative to a stationary viewing position. However, the assumption that an object rotation is equivalent to an observer viewpoint change ignores the potential contribution of extraretinal information that accompanies observer movement. In four experiments, we investigated the role of extraretinal information on real-world object recognition. As in previous studies focusing on the recognition of spatial layouts across view changes, observers performed better in an old/new object recognition task when view changes were caused by viewer movement than when they were caused by object rotation. This difference between viewpoint and orientation changes was due not to the visual background, but to the extraretinal information available during real observer movements. Models of object recognition need to consider other information available to an observer in addition to the retinal projection in order to fully understand object recognition in the real world.     

Sensory information and associative cues used in food detection by wild vervet monkeys

Understanding animals’ spatial perception is a critical step toward discerning their cognitive processes. The spatial sense is multimodal and based on both the external world and mental representations of that world. Navigation in each species depends upon its evolutionary history, physiology, and ecological niche. We carried out foraging experiments on wild vervet monkeys (Chlorocebus pygerythrus) at Lake Nabugabo, Uganda, to determine the types of cues used to detect food and whether associative cues could be used to find hidden food. Our first and second set of experiments differentiated between vervets’ use of global spatial cues (including the arrangement of feeding platforms within the surrounding vegetation) and/or local layout cues (the position of platforms relative to one another), relative to the use of goal-object cues on each platform. Our third experiment provided an associative cue to the presence of food with global spatial, local layout, and goal-object cues disguised. Vervets located food above chance levels when goal-object cues and associative cues were present, and visual signals were the predominant goal-object cues that they attended to. With similar sample sizes and methods as previous studies on New World monkeys, vervets were not able to locate food using only global spatial cues and local layout cues, unlike all five species of platyrrhines thus far tested. Relative to these platyrrhines, the spatial location of food may need to stay the same for a longer time period before vervets encode this information, and goal-object cues may be more salient for them in small-scale space.     

The effects of asymmetry among advisors on the aggregation of their opinions

We investigate the case of a Decision Maker (DM) who obtains probabilistic forecasts regarding the occurrence of a target event from J distinct, asymmetric advisors. In this context, asymmetry is induced by manipulating: (1) amount of information (number of diagnostic cues) available to each advisor and (2) quality (accuracy) of advisors’ previous forecasts. Empirical results from two experiments indicate that the DM’s final estimate can be described as a weighted average of advisor forecasts, where the weights are sensitive to both sources of asymmetry. This work extends the model derived by Budescu and Rantilla (2000) for the DMs confidence in the aggregate to accommodate advisor asymmetry. As in the symmetric case, the DM’s confidence in the weighted average of the forecasts is a function of the number of judges, the total number of cues, the (inferred) inter-judge correlation, and the level of inter-judge overlap in information. The extended model predicts that confidence increases as a function of asymmetry among judges. Empirical results support the main (ordinal) predictions of the model, including the predicted effect of inter-judge asymmetry.     

Cue use by foals (Equus caballus) in a discrimination learning task

Discrimination learning studies suggest that horses learn more easily using spatial than visible object-specific (OS) cues. However, spatial cues have generally confounded intra-array, distal and/or egocentric spatial information. It is also unclear whether conflicting cues compete for association or are redundantly encoded, and furthermore, the influence of prior experiences or training has not been quantified so far. We examined the effect of cue modality on unweaned foals’ performance in a discrimination learning task. After a pilot study confirmed that horses could perform the required OS cue discrimination, nine foals learnt to find food in one of three covered buckets, in any of four positions within a test arena. In Stage 1 the rewarded bucket was signified both by OS cues (pattern) and by relative spatial cues (position). On reaching criterion, cues were separated and foals had to ignore the inappropriate cue (Stage 2). Foals assigned to follow spatial cues (n = 5) completed Stage 2 faster than foals for whom OS cues remained consistent (n = 4). Spatial group foals all reached criterion without delay; no foal in the OS group reached criterion within the testing period. OS group foals initially persisted in responding to the previously correct position, adopting spatially-based strategies when this proved unsuccessful. The findings show for the first time that, even in the absence of distal spatial information, intra-array spatial cues were more salient than OS cues for foals in a food-finding task and learning appeared rather inflexible.     

Money for microbes—Pathogen avoidance and out‐group helping behaviour

Humans have evolved various adaptations against pathogens, including the physiological immune system. However, not all of these adaptations are physiological: the cognitive mechanisms whereby we avoid potential sources of pathogens—for example, disgust elicited by uncleanliness—can be considered as parts of a behavioural immune system (BIS). The mechanisms of BIS extend also to inter‐group relations: Pathogen cues have been shown to increase xenophobia/ethnocentrism, as people prefer to keep their societal in‐group norms unaltered and “clean.” Nonetheless, little is known how pathogen cues influence people's willingness to provide humanitarian aid to out‐group members. We examined how pathogen cues affected decisions of providing humanitarian aid in either instrumental (sending money) or non‐instrumental form (sending personnel to help, or accepting refugees), and whether these effects were moderated by individual differences in BIS sensitivity. Data were collected in two online studies (Ns: 188 and 210). When the hypothetical humanitarian crisis involved a clear risk of infection, participants with high BIS sensitivity preferred to send money rather than personnel or to accept refugees. The results suggest that pathogen cues influence BIS‐sensitive individuals' willingness to provide humanitarian aid when there is a risk of contamination to in‐group members.     

Judgments of happiness during trail running: Pleasure,engagement, and meaning

ObjectivesIt has been theorized that happiness is derived from three major, unique sets of life experience: pleasure, engagement, and meaning. The present study examined the mental processes by which individuals combined five information cues (relatedness, autonomy, competence, mental vitality and physical vitality) when judging the degree of happiness felt by a trail runner during a run.Design/methodThe participants (104 adult male athletes; M_age = 32.70; SD = 10.86) rated pleasure, engagement, and meaning in 32 scenarios built from combinations of these cues.ResultsThe results of multivariate and univariate analyses of variance indicated that all five cues had a positive effect on judgments of pleasure, engagement, and meaning. The participants used three different information integration rules, depending on the pathway to happiness being probed.ConclusionsThe information integration and the integration rules highlighted the different contributions of pleasure, engagement, and meaning in cognitive building of happiness.     

The effects of skill-level and playing-position on the anticipation of ball-bounce in rugby union

The ability to anticipate is a defining feature of skilled sports performance. To date, research investigating the information that underpins skilled anticipation has focused on kinematic information from an opponent and contextual factors. However, there has been a paucity of research investigating the influence of ball-flight and spin. Oval shaped balls, despite the seeming random nature, do in fact display specific bounce characteristics based on the nature of ball-flight. We tested the ability of 38 professional (categorised in to 15 ‘backs’ and 23 ‘forwards’ based on their playing position) and 20 less-skilled rugby union players to anticipate ball bounce direction for grubber and chip kicks using a temporal occlusion paradigm to restrict access to different sources of information. We predicted that skilled performers would have become attuned to both advance postural cues and the physical laws of ball flight and spin that govern ball bounce through their extensive practice and exposure to these situations, and so would anticipate more accurately than less-skilled performers. Results supported this hypothesis as skilled participants outperformed less-skilled in all occlusion conditions, however all groups anticipated more accurately with access to later emerging information sources (i.e., ball spin and rotation) with the skill level difference primarily underpinned by earlier available sources (i.e., advance postural cues). There was no difference between anticipation accuracy in professional forwards and backs and no kick type x group interaction, suggesting that the knowledge structures underpinning perceptual-cognitive expertise are not position specific. Findings have implication for models of anticipation and training design and tactics in rugby.     

Differences in timing and magnitude of lumbopelvic rotation during active and passive knee extension in sitting position in people with and without low back pain: A cross-sectional study

Repetitive lumbopelvic rotation (LPR) during active limb movements has been indicated as a factor that contributes to low back pain (LBP). Prior studies suggest that people with LBP demonstrate greater and earlier LPR during limb movements in prone.We examined timing and magnitude of LPR during sitting active knee extension in people with and without LBP. We also investigated differences of LPR during active and passive knee extension in LBP group. 38 men (mean age: 38.4)10.6) years) with chronic mechanical LBP and 38 matched healthy men (mean age: 36.6(8.4) years) were examined. Kinematic data were collected by motion capture system and analyzed using OpenSim software. The difference between the start time of knee extension and start time of LPR was calculated and was normalized to knee extension movement time. Maximum angular displacement for LPR was also calculated across time.People with LBP demonstrated earlier LPR during knee extension than healthy subjects (P < 0.01). There was, however, no difference in maximum LPR between groups. LBP group also demonstrated greater and earlier LPR during active than during passive knee extension (P < 0.01).Earlier LPR during limb movements in sitting may be related to LBP. Quadriceps muscle activity and inefficient trunk muscles activation may contribute to early LPR in LBP group. A greater understanding of the factors that may contribute to early LPR during daily activities can provide information to guide rehabilitation treatment for people with LBP.     

Auditory clicks distort perceived velocity but only when the system has to rely on extraretinal signals

Previous work has found that repetitive auditory stimulation (click trains) increases the subjective velocity of subsequently presented moving stimuli. We ask whether the effect of click trains is stronger for retinal velocity signals (produced when the target moves across the retina) or for extraretinal velocity signals (produced during smooth pursuit eye movements, when target motion across the retina is limited). In Experiment 1, participants viewed leftward or rightward moving single dot targets, travelling at speeds from 7.5 to 17.5 deg/s. They estimated velocity at the end of each trial. Prior presentation of auditory click trains increased estimated velocity, but only in the pursuit condition, where estimates were based on extraretinal velocity signals. Experiment 2 generalized this result to vertical motion. Experiment 3 found that the effect of clicks during pursuit disappeared when participants tracked across a visually textured background that provided strong local motion cues. Together these results suggest that auditory click trains selectively affect extraretinal velocity signals. This novel finding suggests that the cross-modal integration required for auditory click trains to influence subjective velocity operates at later stages of processing.     

An Impossibility Result for Coherence Rankings

If we receive information from multiple independent and partially reliable information sources, then whether we are justified to believe these information items is affected by how reliable the sources are, by how well the information coheres with our background beliefs and by how internally coherent the information is. We consider the following question. Is coherence a separable determinant of our degree of belief, i.e. is it the case that the more coherent the new information is, the more justified we are in believing the new information, ceteris paribus? We show that if we consider sets of information items of any size (Holism), and if we assume that there exists a coherence Ordering over such sets and that coherence is a function of the probability distribution over the propositions in such sets (Probabilism), then Separability fails to hold.     

Learning where to feed: the use of social information in flower-visiting Pallas’ long-tongued bats (<Emphasis Type="Italic">Glossophaga soricina</Emphasis>)

Social learning is a widespread phenomenon among vertebrates that influences various patterns of behaviour and is often reported with respect to foraging behaviour. The use of social information by foraging bats was documented in insectivorous, carnivorous and frugivorous species, but there are little data whether flower-visiting nectarivorous bats (Phyllostomidae: Glossophaginae) can acquire information about food from other individuals. In this study, we conducted an experiment with a demonstrator-observer paradigm to investigate whether flower-visiting Pallas’ long-tongued bats (Glossophaga soricina) are able to socially learn novel flower positions via observation of, or interaction with, knowledgeable conspecifics. The results demonstrate that flower-visiting G. soricina are able to use social information for the location of novel flower positions and can thereby reduce energy-costly search efforts. This social transmission is explainable as a result of local enhancement; learning bats might rely on both visual and echo-acoustical perception and are likely to eavesdrop on auditory cues that are emitted by feeding conspecifics. We additionally tested the spatial memory capacity of former demonstrator bats when retrieving a learned flower position, and the results indicate that flower-visiting bats remember a learned flower position after several weeks.     

Contribution of extraretinal signals to the scaling of object distance during self-motion

We investigated the role of extraretinal information in the perception of absolute distance. In a computer-simulated environment, monocular observers judged the distance of objects positioned at different locations in depth while performing frontoparallel movements of the head. The objects were spheres covered with random dots subtending three different visual angles. Observers viewed the objects ateye level, either in isolation or superimposed on a ground floor. The distance and size of the spheres were covaried to suppress relative size information. Hence, the main cues to distance were the motion parallax and the extraretinal signals. In three experiments, we found evidence that (1) perceived distance is correlated with simulated distance in terms of precision and accuracy, (2) the accuracy in the distance estimate is slightly improved by the presence of a ground-floor surface, (3) the perceived distance is not altered significantly when the visual field size increases, and (4) the absolute distance is estimated correctly during self-motion. Conversely, stationary subjects failed to report absolute distance when they passively observed a moving object producing the same retinal stimulation, unless they could rely on knowledge of the three-dimensional movements.     

Two-category place representations persist over body rotations

We explored a system that constructs environment-centered frames of reference and coordinates memory for the azimuth of an object in an enclosed space. For one group, we provided two environmental cues (doors): one in the front, and one in the rear. For a second group, we provided two object cues: a front and a rear cue. For a third group, we provided no external cues; we assumed that for this group, their reference frames would be determined by the orthogonal geometry of the floor-and-wall junction that divides a space in half or into multiple territories along the horizontal continuum. Using Huttenlocher, Hedges, and Duncan’s (Psychological Review 98: 352-376, 1991) category-adjustment model (cue-based fuzzy boundary version) to fit the data, we observed different reference frames than have been seen in prior studies involving two-dimensional domains. The geometry of the environment affected all three conditions and biased the remembered object locations within a two-category (left vs. right) environmental frame. The influence of the environmental geometry remained observable even after the participants’ heading within the environment changed due to a body rotation, attenuating the effect of the front but not of the rear cue. The door and object cues both appeared to define boundaries of spatial categories when they were used for reorientation. This supports the idea that both types of cues can assist in environment-centered memory formation.     

The perception of shape and curvedness from binocular stereopsis and structure from motion

The integration of binocular stereopsis and kinetic depth was measured for two distinct aspects of 3-Dstructure: (1)shape index, which is a measure of scale-independent structure, and (2)curvedness, which is a measure of scale-dependent structure. We found that motion contributes significantly more to judged shape index than it does to judged curvedness, and stereo contributes significantly more to judged curvedness than it does to judged shape index. This suggests that the differences in the relative contribution of motion and stereo reported here occurred because these two sources do not equally specify the scale-dependent and scale-independent aspects of surface structure. Furthermore, these results seem to be inconsistent with integration models in which the different visual cues all initially contribute to the same single representation of 3-Dstructure.