Experience dependent changes in odour-viscosity perception

One consequence of experiencing flavour — the combination of taste, smell and somatosensation that occurs during ingestion — is that it can result in perceptual changes for the odour component, when this is later smelled alone. One such change is the acquisition of taste-like properties, but whether odours can also acquire somatosensory-like qualities is largely unknown. Participants here were exposed to one odour sampled in a viscous solution, another sampled in a sweet/viscous solution, and a further odour sampled in water. The odour sampled in the sweet/viscous solution was, when later sniffed alone, judged to smell thicker and sweeter, than the other two odours. Similarly, when the sweet/viscous paired odour was added to a viscous solution, the combination was judged as more viscous, than the other two odours — and sweeter when added to a sweet solution. This experiment suggests that odours can acquire tactile-like somatosensory qualities and this may best occur when a taste is present during learning. Recent work indicates that tastes may be superior to somatosensory stimuli alone in promoting flavour binding, a seeming precondition for this type of learning.     

Haptic mental rotation revisited: multiple reference frame dependence

The nature of reference frames involved in haptic spatial processing was addressed by means of a haptic mental rotation task. Participants assessed the parity of two objects located in various spatial locations by exploring them with different hand orientations. The resulting response times were fitted with a triangle wave function. Phase shifts were found to depend on the relation between the hands and the objects, and between the objects and the body. We rejected the possibility that a single reference frame drives spatial processing. Instead, we found evidence of multiple interacting reference frames with the hand-centered reference frame playing the dominant role. We propose that a weighted average of the allocentric, the hand-centered and the body-centered reference frames influences the haptic encoding of spatial information. In addition, we showed that previous results can be reinterpreted within the framework of multiple reference frames. This mechanism has proved to be ubiquitously present in haptic spatial processing.     

Spatial patterns in tactile perception: is there a tactile field?

Previous studies of tactile spatial perception focussed either on a single point of stimulation, on local patterns within a single skin region such as the fingertip, on tactile motion, or on active touch. It remains unclear whether we should speak of a tactile field, analogous to the visual field, and supporting spatial relations between stimulus locations. Here we investigate this question by studying perception of large-scale tactile spatial patterns on the hand, arm and back. Experiment 1 investigated the relation between perception of tactile patterns and the identification of subsets of those patterns. The results suggest that perception of tactile spatial patterns is based on representing the spatial relations between locations of individual stimuli. Experiment 2 investigated the spatial and temporal organising principles underlying these relations. Experiment 3 showed that tactile pattern perception makes reference to structural representations of the body, such as body parts separated by joints. Experiment 4 found that precision of pattern perception is poorer for tactile patterns that extend across the midline, compared to unilateral patterns. Overall, the results suggest that the human sense of touch involves a tactile field, analogous to the visual field. The tactile field supports computation of spatial relations between individual stimulus locations, and thus underlies tactile pattern perception.     

Asymmetric cross-modal effects in time perception

It is common to judge the duration of an audiovisual event, and yet it remains controversial how the judgment of duration is affected by signals from other modalities. We used an oddball paradigm to examine the effect of sound on the judgment of visual duration and that of a visual object on the judgment of an auditory duration. In a series of standards and oddballs, the participants compared the duration of the oddballs to that of the standards. Results showed asymmetric cross-modal effects, supporting the auditory dominance hypothesis: a sound extends the perceived visual duration, whereas a visual object has no effect on perceived auditory duration. The possible mechanisms (pacemaker or mode switch) proposed in the Scalar Expectancy Theory [Gibbon, J., Church, R. M., & Meck, W. H. (1984). Scalar timing in memory. In J. Gibbon & L. Allan (Eds.), Annals of the New York Academy of Sciences: Vol. 423. Timing and time perception (pp. 52–77). New York: New York Academy of Sciences] were examined using different standard durations. We conclude that sound increases the perceived visual duration by accelerating the pulse rate in the visual pacemaker.     

Crossmodal associations between flavoured milk solutions and musical notes

A number of crossmodal associations have now been described in the context of food evaluation, such as between tastes or flavours and musical notes (Crisinel & Spence, 2010b). Here we extend these findings by presenting flavoured milk solutions of varying fat contents. The participants in the present study matched a series of milk samples to musical notes. They chose both the pitch and the class of instrument that they felt was most appropriate for each sample. Participants also rated various features of the samples, such as their pleasantness, bitterness, or familiarity. Consistent associations between flavours and both pitch and instruments were confirmed. However, fat content did not influence either the pitch or instrument chosen, although it did have an effect on pleasantness and intensity ratings. These results demonstrate that flavour–sound associations are not restricted to basic tastes and flavours presented individually, but are still present in the context of more complex food stimuli. The present study opens the way for further investigations into the nature and characteristics of crossmodal associations (or correspondences) between more complex stimuli, both in the auditory and gustatory/olfactory modalities. This novel approach could lead to new insights into the representation of chemosensory stimuli in humans.     

Can 15-month-old infants understand pretence? An investigation using the 'violation-of-expectation' paradigm

Productive tests are unsuitable for measuring infants' earliest understanding of pretence, because performance demands may render infants unable to produce the actions required to pass the test. Recently, Onishi, Baillargeon and Leslie (2007) used the violation-of-expectation (VOE) paradigm as a measure of infants' understanding of others' pretence that is free from such performance demands. They found that 15-month-old infants looked longer at an Unexpected event in which an actor pretended to pour into one cup but pretended to drink from another cup, compared to pretending to pour and drink with the same cup. On this basis, they argued that 15-month-old infants expect others' pretence to be consistent, demonstrating their understanding of others' pretence. However, infants may have responded to expectations they had about familiar action sequences, rather than to pretence per se. To test this hypothesis, the current study firstly replicated Onishi et al.'s results in a sample of 28 typically developing 15-month-old infants, and then added a condition using closely matched real versions of their pretend VOE tasks. It was found that infants looked longer at unexpected events, whether or not the events were real or pretend. It was concluded that 15-month-old infants may look longer at pretend events due to violations of expectations they have about familiar action sequences, rather than because they understand others' pretence behaviour.     

Common functional principal components analysis: a new approach to analyzing human movement data

In many human movement studies angle-time series data on several groups of individuals are measured. Current methods to compare groups include comparisons of the mean value in each group or use multivariate techniques such as principal components analysis and perform tests on the principal component scores. Such methods have been useful, though discard a large amount of information. Functional data analysis (FDA) is an emerging statistical analysis technique in human movement research which treats the angle-time series data as a function rather than a series of discrete measurements. This approach retains all of the information in the data. Functional principal components analysis (FPCA) is an extension of multivariate principal components analysis which examines the variability of a sample of curves and has been used to examine differences in movement patterns of several groups of individuals. Currently the functional principal components (FPCs) for each group are either determined separately (yielding components that are group-specific), or by combining the data for all groups and determining the FPCs of the combined data (yielding components that summarize the entire data set). The group-specific FPCs contain both within and between group variation and issues arise when comparing FPCs across groups when the order of the FPCs alter in each group. The FPCs of the combined data may not adequately describe all groups of individuals and comparisons between groups typically use t-tests of the mean FPC scores in each group. When these differences are statistically non-significant it can be difficult to determine how a particular intervention is affecting movement patterns or how injured subjects differ from controls. In this paper we aim to perform FPCA in a manner allowing sensible comparisons between groups of curves. A statistical technique called common functional principal components analysis (CFPCA) is implemented. CFPCA identifies the common sources of variation evident across groups but allows the order of each component to change for a particular group. This allows for the direct comparison of components across groups. We use our method to analyze a biomechanical data set examining the mechanisms of chronic Achilles tendon injury and the functional effects of orthoses.     

Interaction between stimulus-driven orienting and top-down modulation in attentional capture

The present study investigated whether visual and kinesthetic stimuli are stored as multisensory or modality-specific representations in unimodal and crossmodal working memory tasks. To this end, angle-shaped movement trajectories were presented to 16 subjects in delayed matching-to-sample tasks either visually or kinesthetically during encoding and recognition. During the retention interval, a secondary visual or kinesthetic interference task was inserted either immediately or with a delay after encoding. The modality of the interference task interacted significantly with the encoding modality. After visual encoding, memory was more impaired by a visual than by a kinesthetic secondary task, while after kinesthetic encoding the pattern was reversed. The time when the secondary task had to be performed interacted with the encoding modality as well. For visual encoding, memory was more impaired, when the secondary task had to be performed at the beginning of the retention interval. In contrast, memory after kinesthetic encoding was more affected, when the secondary task was introduced later in the retention interval. The findings suggest that working memory traces are maintained in a modality-specific format characterized by distinct consolidation processes that take longer after kinesthetic than after visual encoding.     

Conditions of directed attention inhibit recognition performance for explicitly presented target-aligned irrelevant stimuli

The fate of irrelevant and overtly presented stimuli that was temporally aligned with an attended target in a separate task was explored. Seitz and Watanabe (2003) demonstrated that if an irrelevant motion stimulus was implicit (i.e., subthreshold), a later facilitation for the same motion direction was observed if the previously presented implicit motion (of the same direction) was temporally aligned with the presence of an attended target. Later research, however, demonstrated that if the motion stimulus aligned with the attended target was explicit (i.e., suprathreshold), a later inhibition was observed (Tsushima, Seitz, & Watanabe, 2008). The current study expands on this by using more salient stimuli (words and pictures) in an inattentional blindness paradigm, and suggests that when attention is depleted, recognition for target-aligned task-irrelevant items is impaired in a subsequent recognition task. Participants were required to respond to either immediate picture, or word, repetitions in a stream of simultaneously presented line drawings and written words, and later given a surprise recognition test that measured recognition for the words or the pictures. When analyzing word recognition performance after attention had been directed to the pictures, words that had appeared simultaneously with a picture repetition in the repetition detection task were recognized at levels significantly below chance. The same inhibition was mirrored when testing for picture recognition after having attended to the words in the repetition detection task. These data suggest an inhibitory mechanism that is exhibited in later recognition tests for salient information that was previously unattended and had been simultaneously being presented with an attended target in a different task.     

An imputed dissociation might be an artifact: Further evidence for the generalizability of the observations of Durgin et al. 2010

We recently showed that palm board measures are systematically inaccurate for full-cue surfaces within reach of one's hand, whereas free-hand gestures and reaching actions are quite accurate for such surfaces (Durgin, Hajnal, Li, Tonge, & Stigliani, 2010). Proffitt and Zadra (2010) claim that our demonstration that palm boards are highly inaccurate is irrelevant to interpreting past and present findings concerning dissociations between verbal reports and palm board estimates. In their paper they offer a theoretical representation of the findings of Bhalla and Proffitt (1999) and argue that our analysis is incompatible with their account. We offer here an alternative account of the findings of Bhalla and Proffitt, based on their actual data (which are fully compatible with our original analysis). We further show how our account generalizes to more recent studies that continue (1) to mistakenly describe null statistical effects on (insensitive) palm boards as evidence of a “dissociation” from (more sensitive) verbal measures that show a similar relative magnitude of change and (2) to introduce uncontrolled demand characteristics.     

Attention and suppression affect tactile perception in reach-to-grasp movements

Reaching with the hand is characterized by a decrease in sensitivity to tactile stimuli presented to the moving hand. Here, we investigated whether tactile suppression can be canceled by attentional orienting. In a first experiment, participants performed a dual-task involving a goal-directed movement paired with the speeded detection of a tactile pulse. The pulse was either delivered to the moving or stationary hand, during movement preparation, execution, or the post-movement phase. Furthermore, stimulation was delivered with equal probability to either hand, or with a higher probability to either the moving or resting hand. The results highlighted faster RTs under conditions of higher probability of stimulation delivery to both moving and resting hands, thus indicating an attentional effect. For the motor preparation period, RTs were faster only at the resting hand under conditions where tactile stimulation was more likely to be delivered there. In a second experiment, a non-speeded perceptual task was used as a secondary task and tactile discrimination thresholds were recorded. Tactile stimulation was delivered concomitantly at both index fingers either in the movement preparation period (both before and after the selection of the movement effector had taken place), in the motor execution period, or, in a control condition, in the time-window of motor execution, but the movement of the hand was restrained. In the preparation period, tactile thresholds were comparable for the two timings of stimulation delivery; i.e., before and after the selection of the movement effector had taken place. These results therefore suggest that shortly prior to, and during, the execution of goal-directed movements, a combined facilitatory and inhibitory influence acts on tactile perception.     

Human movement variability, nonlinear dynamics, and pathology: is there a connection?

Fields studying movement generation, including robotics, psychology, cognitive science, and neuroscience utilize concepts and tools related to the pervasiveness of variability in biological systems. The concept of variability and the measures for nonlinear dynamics used to evaluate this concept open new vistas for research in movement dysfunction of many types. This review describes innovations in the exploration of variability and their potential importance in understanding human movement. Far from being a source of error, evidence supports the presence of an optimal state of variability for healthy and functional movement. This variability has a particular organization and is characterized by a chaotic structure. Deviations from this state can lead to biological systems that are either overly rigid and robotic or noisy and unstable. Both situations result in systems that are less adaptable to perturbations, such as those associated with unhealthy pathological states or absence of skillfulness.     

The learning of 90° continuous relative phase with and without Lissajous feedback: external and internally generated bimanual coordination

Results from recent experiments (e.g., Kovacs, Buchanan, & Shea, 2009a–b, 2010a,b) suggest that when salient visual information is presented using Lissajous plots bimanual coordination patterns typically thought to be very difficult to perform without extensive practice can be performed with remarkably low relative phase error and variability with 5 min or less of practice. However, when this feedback is removed, performance deteriorates. The purpose of the present experiment was to determine if reducing the frequency of feedback presentation will decrease the participant's reliance on the feedback and will facilitate the development of an internal representation capable of sustaining performance when the Lissajous feedback is withdrawn. The results demonstrated that reduced frequency Lissajous feedback results in very effective bimanual coordination performance on tests with Lissajous feedback available and when feedback is withdrawn. Taken together the present experiments add to the growing literature that supports the notion that salient perceptual information can override some aspects of the system's intrinsic dynamics typically linked to motor output control. Additionally, the present results suggest that the learning of both externally and internally driven bimanual coordination is facilitated by providing reduced frequency Lissajous feedback.     

Artificial neural networks for analyzing inter-limb coordination: the golf chip shot

Motor control research relies on theories, such as coordination dynamics, adapted from physical sciences to explain the emergence of coordinated movement in biological systems. Historically, many studies of coordination have involved inter-limb coordination of relatively few degrees of freedom. This study looked at the high-dimensional inter-limb coordination used to perform the golf chip shot toward six different target distances. This study also introduces a visualization of high-dimensional coordination relevant within the coordination dynamics theoretical framework. A specific type of Artificial Neural Network (ANN), the Self-Organizing Map (SOM), was used for the analysis. In this study, the trajectory of consecutive best-matching nodes on the output map was used as a collective variable and subsequently fed into a second SOM which was used to create visualization of coordination stability. The SOM trajectories showed changes in coordination between movement patterns used for short chip shots and movement patterns used for long chip shots. The attractor diagrams showed non-linear phase transitions for three out of four players. The methods used in this study may offer a solution for researchers from a coordination dynamics perspective who intend to use data obtained from discrete high-dimensional movements.     

Similarity and categorization: from vision to touch

Even though human perceptual development relies on combining multiple modalities, most categorization studies so far have focused on the visual modality. To better understand the mechanisms underlying multisensory categorization, we analyzed visual and haptic perceptual spaces and compared them with human categorization behavior. As stimuli we used a three-dimensional object space of complex, parametrically-defined objects. First, we gathered similarity ratings for all objects and analyzed the perceptual spaces of both modalities using multidimensional scaling analysis. Next, we performed three different categorization tasks which are representative of every-day learning scenarios: in a fully unconstrained task, objects were freely categorized, in a semi-constrained task, exactly three groups had to be created, whereas in a constrained task, participants received three prototype objects and had to assign all other objects accordingly. We found that the haptic modality was on par with the visual modality both in recovering the topology of the physical space and in solving the categorization tasks. We also found that within-category similarity was consistently higher than across-category similarity for all categorization tasks and thus show how perceptual spaces based on similarity can explain visual and haptic object categorization. Our results suggest that both modalities employ similar processes in forming categories of complex objects.     

I see into your mind too well: working memory adjusts the probability judgment of others' mental states

Although an increasing number of studies on adults have indicated that working memory (WM) contributes to the ability to understand the mental states of others (i.e., theory of mind), the detailed mechanism by which WM contributes to successful reasoning has not previously been revealed. This study shows that WM modulates the degree of attribution of one's own knowledge to others' mental states. Participants were asked to read a story twice (Experiment 2) or as carefully as possible (Experiment 3) and to estimate the probability percentages of possible choices for a naive protagonist's behavior. The participants were then asked to maintain either a two- or seven-letter alphabet string (i.e., a light or heavy WM load, respectively) during the probability estimation but not during the story comprehension. The results showed that compared to the participants with a light WM load, those with a heavy WM load estimated a significantly higher probability of the choice indicating that the protagonist would behave on the basis of a fact that the participants knew but the protagonist did not. This result indicates that WM moderates the extent to which adults attribute their own knowledge to others' mental states. The role of WM in theory of mind and in heuristic strategy for making probability judgments was then discussed.     

Muscle coordination and force variability during static and dynamic tracking tasks

This study examined muscular activity patterns of extensor and flexor muscles and variability of forces during static and dynamic tracking tasks using compensatory and pursuit display. Fourteen volunteers performed isometric actions in two conditions: (i) a static tracking task consisting of flexion/pronation, ulnar deviation, extension/supination and radial deviation of the wrist at 20% maximum voluntary contraction (MVC), and (ii) a dynamic tracking task aiming at following a moving target at 20% MVC in the four directions of contraction. Surface electromyography (SEMG) from extensor carpi ulnaris, extensor carpi radialis, flexor carpi ulnaris and flexor digitorum superficialis muscles and exerted forces in the transverse and sagittal plane were recorded. Normalized root mean square and mutual information (index of functional connectivity within muscles) of SEMGs and the standard deviation and sample entropy of force signals were extracted. Larger SEMG amplitudes were found for the dynamic task (p < .05), while normalized mutual information between muscle pairs was larger for the static task (p < .05). Larger size of variability (standard deviation of force) concomitant with smaller sample entropy was observed for the dynamic task compared with the static task (p < .01 for both). These findings underline a rescaling of the muscles’ respective contribution influencing force variability relying on feedback and feed-forward control strategies in relation to display modes during static and dynamic tracking tasks.     

Judging the 'passability' of dynamic gaps in a virtual rugby environment

Affordances have recently been proposed as a guiding principle in perception–action research in sport (Fajen, Riley, & Turvey, 2009). In the present study, perception of the ’passability’ affordance of a gap between two approaching defenders in rugby is explored. A simplified rugby gap closure scenario was created using immersive, interactive virtual reality technology where 14 novice participants (attacker) judged the passability of the gap between two virtual defenders via a perceptual judgment (button press) task. The scenario was modeled according to tau theory (Lee, 1976) and a psychophysical function was fitted to the response data. Results revealed that a tau-based informational quantity could account for 82% of the variance in the data. Findings suggest that the passability affordance in this case, is defined by this variable and participants were able to use it in order to inform prospective judgments as to passability. These findings contribute to our understanding of affordances and how they may be defined in this particular sporting scenario; however, some limitations regarding methodology, such as decoupling perception and action are also acknowledged.     

Conflict and error adaptation in the Simon task

We present recent empirical and theoretical advances in conflict and error monitoring in the Simon task. On the basis of the adaptation by binding account for conflict adaptation and the orienting account for post-error slowing, we predict a dissociation between conflict and error monitoring. This prediction is tested and confirmed as conflict adaptation is task-specific while post-error slowing is not.     

Encoding time and signs exposure time in the representation of diagrammatic deontic meanings

It has been proposed that prohibition and obligation be represented in different ways in reasoning with deontic information (Bucciarelli & Johnson-Laird, 2005). Obligations are salient in permissible situations and prohibitions in impermissible situations. In some specific cases, differential initial representations are also consistently predicted from the comprehension of negations, if prohibition is considered as the negation of an obligation. Three experiments evaluate whether traffic signs of prohibition and obligation speed up the response time to the proposed direction represented and whether this advantage remains when people have more time to think. When making judgements about the manoeuvre performed by a vehicle, participants' response times are consistent with the predicted representation when they have a short time (i.e., 300 ms) to understand the premise. In this case they represent what is permissible by obligatory signs and also what is impermissible by prohibitory signs. However, if they have more time (i.e., 1000 ms) to understand the premise, they still represent what is permissible by obligatory signs but they seem to change their initial representations to what is permissible by prohibitory signs.