Developmental changes in audiotactile event perception.

The fission and fusion illusions provide measures of multisensory integration. The sound-induced tap fission illusion occurs when a tap is paired with two distractor sounds, resulting in the perception of two taps; the sound-induced tap fusion illusion occurs when two taps are paired with a single sound, resulting in the perception of a single tap. Using these illusions, we measured integration in three groups of children (9-, 11-, and 13-year-olds) and compared them with a group of adults. Based on accuracy, we derived a measure of magnitude of illusion and used a signal detection analysis to estimate perceptual discriminability and decisional criterion. All age groups showed a significant fission illusion, whereas only the three groups of children showed a significant fusion illusion. When compared with adults, the 9-year-olds showed larger fission and fusion illusions (i.e., reduced discriminability and greater bias), whereas the 11-year-olds were adult-like for fission but showed some differences for fusion: significantly worse discriminability and marginally greater magnitude and criterion. The 13-year-olds were adult-like on all measures. Based on the pattern of data, we speculate that the developmental trajectories for fission and fusion differ. We discuss these developmental results in the context of three non-mutually exclusive theoretical frameworks: sensory dominance, maximum likelihood estimation, and causal inference.

The development of audio-visual temporal precision precedes its rapid recalibration.

Through development, multisensory systems reach a balance between stability and flexibility: the systems integrate optimally cross-modal signals from the same events, while remaining adaptive to environmental changes. Is continuous intersensory recalibration required to shape optimal integration mechanisms, or does multisensory integration develop prior to recalibration? Here, we examined the development of multisensory integration and rapid recalibration in the temporal domain by re-analyzing published datasets for audio-visual, audio-tactile, and visual-tactile combinations. Results showed that children reach an adult level of precision in audio-visual simultaneity perception and show the first sign of rapid recalibration at 9 years of age. In contrast, there was very weak rapid recalibration for other cross-modal combinations at all ages, even when adult levels of temporal precision had developed. Thus, the development of audio-visual rapid recalibration appears to require the maturation of temporal precision. It may serve to accommodate distance-dependent travel time differences between light and sound.

Imagine Your Crossed Hands as Uncrossed: Visual Imagery Impacts the Crossed-Hands Deficit.

Successful interaction with our environment requires accurate tactile localization. Although we seem to localize tactile stimuli effortlessly, the processes underlying this ability are complex. This is evidenced by the crossed-hands deficit, in which tactile localization performance suffers when the hands are crossed. The deficit results from the conflict between an internal reference frame, based in somatotopic coordinates, and an external reference frame, based in external spatial coordinates. Previous evidence in favour of the integration model employed manipulations to the external reference frame (e.g., blindfolding participants), which reduced the deficit by reducing conflict between the two reference frames. The present study extends this finding by asking blindfolded participants to visually imagine their crossed arms as uncrossed. This imagery manipulation further decreased the magnitude of the crossed-hands deficit by bringing information in the two reference frames into alignment. This imagery manipulation differentially affected males and females, which was consistent with the previously observed sex difference in this effect: females tend to show a larger crossed-hands deficit than males and females were more impacted by the imagery manipulation. Results are discussed in terms of the integration model of the crossed-hands deficit.

Exploring Reference Frame Integration Using Response Demands in a Tactile Temporal-Order Judgement Task.

Exploring the world through touch requires the integration of internal (e.g., anatomical) and external (e.g., spatial) reference frames - you only know what you touch when you know where your hands are in space. The deficit observed in tactile temporal-order judgements when the hands are crossed over the midline provides one tool to explore this integration. We used foot pedals and required participants to focus on either the hand that was stimulated first (an anatomical bias condition) or the location of the hand that was stimulated first (a spatiotopic bias condition). Spatiotopic-based responses produce a larger crossed-hands deficit, presumably by focusing observers on the external reference frame. In contrast, anatomical-based responses focus the observer on the internal reference frame and produce a smaller deficit. This manipulation thus provides evidence that observers can change the relative weight given to each reference frame. We quantify this effect using a probabilistic model that produces a population estimate of the relative weight given to each reference frame. We show that a spatiotopic bias can result in either a larger external weight (Experiment 1) or a smaller internal weight (Experiment 2) and provide an explanation of when each one would occur.

Haptic awareness changes when lying down.

Accurate localization of touch requires the integration of two reference frames-an internal (e.g., anatomical) and an external (e.g., spatial). Using a tactile temporal order judgement task with the hands crossed over the midline, we investigated the integration of these two reference frames. We manipulated the reliability of the visual and vestibular information, both of which contribute to the external reference frame. Visual information was manipulated between experiments (Experiment 1 was done with full vision and Experiment 2 was done while wearing a blindfold). Vestibular information was manipulated in both experiments by having the two groups of participants complete the task in both an upright posture and one where they were lying down on their side. Using a Bayesian hierarchical model, we estimated the perceptual weight applied to these reference frames. Lying participants on their side reduced the weight applied to the external reference frame and produced a smaller deficit; blindfolding resulted in similar reductions. These findings reinforce the importance of the visual system when weighting tactile reference frames, and highlight the importance of the vestibular system in this integration.

Reliability of the Crossed-Hands Deficit in Tactile Temporal Order Judgements.

Crossing the hands over the midline impairs performance on a tactile temporal order judgement (TOJ) task, resulting in the crossed-hands deficit. This deficit results from a conflict between two reference frames - one internal (somatotopic) and the other external (spatial) - for coding stimulus location. The substantial individual differences observed in the crossed-hands deficit highlight the differential reliance on these reference frames. For example, women have been reported to place a greater emphasis on the external reference frame than men, resulting in a larger crossed-hands deficit for women. It has also been speculated that individuals with an eating disorder place a greater weight on the external reference frame. Further exploration of individual differences in reference frame weighing using a tactile TOJ task requires that the reliability of the task be established. In Experiment 1, we investigated the reliability of the tactile TOJ task across two sessions separated by one week and found high reliability in the magnitude of the crossed-hands deficit. In Experiment 2, we report the split-half reliability across multiple experiments (both published and unpublished). Overall, tactile TOJ reliability was high. Experiments with small to moderate crossed-hands deficits showed good reliability; those with larger deficits showed even higher reliability. Researchers should try to maximize the size of the effect when interested in individual differences in the use of the internal and external reference frames.

Developmental changes in the perception of audiotactile simultaneity.

We charted the developmental trajectory of the perception of audiotactile simultaneity by testing three groups of children (aged 7, 9, and 11 years) and one group of adults. A white noise burst and a tap to the index finger were presented at 1 of 13 stimulus onset asynchronies (SOAs), and the participants were asked to report whether the two stimuli were simultaneous. Compared with adults, 7-year-olds made significantly more simultaneous responses at 9 of the 13 SOAs, whereas 9-year-olds differed from adults at only 2 SOAs. The precision of simultaneity perception was lower, and response errors were higher, in younger children than in adults. The 11-year-olds were adult-like on all measures, thereby demonstrating that judgments about simultaneity for audiotactile stimuli are mature by 11 years. This developmental pattern is similar to that for simultaneity perception for visuotactile stimuli but later than that for audiovisual stimuli. The longer developmental trajectories of the perception of simultaneity between touch and vision and between touch and audition may arise from the need to coordinate and recalibrate between different reference frames and different neural transmission times in each sensory system during body growth; in addition, the ubiquity of audiovisual experience in everyday life may accelerate the development of that modality pairing.

Developmental changes in the perception of visuotactile simultaneity.

A simultaneity judgment (SJ) task was used to measure the developmental trajectory of visuotactile simultaneity perception in children (aged 7, 9, 11, and 13 years) and adults. Participants were presented with a visual flash in the center of a computer monitor and a tap on their right index finger (located 20° below the flash) with 13 possible stimulus onset asynchronies (SOAs). Participants reported whether the flash and tap were presented at the same time. Compared with the adult group, children aged 7 and 9 years made more simultaneous responses when the tap led by more than 300 ms and when the flash led by more than 200 ms, whereas they made fewer simultaneous responses at the 0 ms SOA. Model fitting demonstrated that the window of visuotactile simultaneity became narrower with development and reached adult-like levels between 9 and 11 years of age. Response errors decreased continuously until 11 years of age. The point of subjective simultaneity (PSS) was located on the tactile-leading side in all participants tested, indicating that 7-year olds (the youngest age tested) are adult-like on this measure. In summary, the perception of visuotactile simultaneity is not fully mature until 11 years of age. The protracted development of visuotactile simultaneity perception may be related to the need for crossmodal recalibration as the body grows and to the developmental improvements in the ability to optimally integrate visual and tactile signals.

Perceptual similarity induces overinvestment in an attentional blink task.

The overinvestment account of the attentional blink (AB) posits that the AB results from the allocation of more resources than necessary to encode a first target (T1), which in turn lowers the resources available to encode a second target (T2) shortly thereafter. Across two experiments, we examined whether resource allocation to T1, and thus overinvestment that results in an AB effect, might be limited by perceptual mechanisms that evaluate the need for encoding resources. The key result observed in both experiments was that a relatively easy to encode T1 can nonetheless result in an AB when it is perceptually similar to a more difficult to encode T1. The importance of experimental context as an influence on the allocation, or overinvestment, of attentional resources to T1 is highlighted by these findings.

Central-peripheral differences in audiovisual and visuotactile event perception.

We examined audiovisual and visuotactile integration in the central and peripheral visual field using visual fission and fusion illusions induced by sounds or taps. The fission illusion occurs when a single flash is perceived as two flashes if paired with two beeps or taps; the fusion illusion, by contrast, occurs when two flashes are perceived as a single flash if the flashes are paired with a single beep or tap. Beeps and taps induced similar patterns of illusions: the fission illusion was larger in the periphery than in the center, whereas the fusion illusion was larger in the center than in the periphery. An analysis based on signal detection theory revealed that both a decline in discriminability and a shift in criterion were associated with the more pronounced fission induced by sounds in the periphery. In contrast, only a shift in criterion was associated with the larger fission induced by taps in the periphery, and the larger fusion induced by a sound or tap in the center. To accommodate these findings, two accounts are proposed: audiovisual signals are more likely to be integrated in peripheral than in central vision, and the interpretation of visual signals favors discontinuous percepts, especially in the periphery.

Sliding into happiness: A new tool for measuring affective responses to words.

Reliable measurement of affective responses is critical for research into human emotion. Affective evaluation of words is most commonly gauged on multiple dimensions-including valence (positivity) and arousal-using a rating scale. Despite its popularity, this scale is open to criticism: It generates ordinal data that is often misinterpreted as interval, it does not provide the fine resolution that is essential by recent theoretical accounts of emotion, and its extremes may not be properly calibrated. In 5 experiments, the authors introduce a new slider tool for affective evaluation of words on a continuous, well-calibrated and high-resolution scale. In Experiment 1, participants were shown a word and asked to move a manikin representing themselves closer to or farther away from the word. The manikin's distance from the word strongly correlated with the word's valence. In Experiment 2, individual differences in shyness and sociability elicited reliable differences in distance from the words. Experiment 3 validated the results of Experiments 1 and 2 using a demographically more diverse population of responders. Finally, Experiment 4 (along with Experiment 2) suggested that task demand is not a potential cause for scale recalibration. In Experiment 5, men and women placed a manikin closer or farther from words that showed sex differences in valence, highlighting the sensitivity of this measure to group differences. These findings shed a new light on interactions among affect, language, and individual differences, and demonstrate the utility of a new tool for measuring word affect. (PsycINFO Database Record

Early Binocular Input Is Critical for Development of Audiovisual but Not Visuotactile Simultaneity Perception.

Temporal simultaneity provides an essential cue for integrating multisensory signals into a unified perception. Early visual deprivation, in both animals and humans, leads to abnormal neural responses to audiovisual signals in subcortical and cortical areas [1-5]. Behavioral deficits in integrating complex audiovisual stimuli in humans are also observed [6, 7]. It remains unclear whether early visual deprivation affects visuotactile perception similarly to audiovisual perception and whether the consequences for either pairing differ after monocular versus binocular deprivation [8-11]. Here, we evaluated the impact of early visual deprivation on the perception of simultaneity for audiovisual and visuotactile stimuli in humans. We tested patients born with dense cataracts in one or both eyes that blocked all patterned visual input until the cataractous lenses were removed and the affected eyes fitted with compensatory contact lenses (mean duration of deprivation = 4.4 months; range = 0.3-28.8 months). Both monocularly and binocularly deprived patients demonstrated lower precision in judging audiovisual simultaneity. However, qualitatively different outcomes were observed for the two patient groups: the performance of monocularly deprived patients matched that of young children at immature stages, whereas that of binocularly deprived patients did not match any stage in typical development. Surprisingly, patients performed normally in judging visuotactile simultaneity after either monocular or binocular deprivation. Therefore, early binocular input is necessary to develop normal neural substrates for simultaneity perception of visual and auditory events but not visual and tactile events.

The development of the perception of audiovisual simultaneity.

We measured the typical developmental trajectory of the window of audiovisual simultaneity by testing four age groups of children (5, 7, 9, and 11 years) and adults. We presented a visual flash and an auditory noise burst at various stimulus onset asynchronies (SOAs) and asked participants to report whether the two stimuli were presented at the same time. Compared with adults, children aged 5 and 7 years made more simultaneous responses when the SOAs were beyond ± 200 ms but made fewer simultaneous responses at the 0 ms SOA. The point of subjective simultaneity was located at the visual-leading side, as in adults, by 5 years of age, the youngest age tested. However, the window of audiovisual simultaneity became narrower and response errors decreased with age, reaching adult levels by 9 years of age. Experiment 2 ruled out the possibility that the adult-like performance of 9-year-old children was caused by the testing of a wide range of SOAs. Together, the results demonstrate that the adult-like precision of perceiving audiovisual simultaneity is developed by 9 years of age, the youngest age that has been reported to date.

An attentional bias for LEGO® people using a change detection task: Are LEGO® people animate?

Animate objects have been shown to elicit attentional priority in a change detection task. This benefit has been seen for both human and nonhuman animals compared with inanimate objects. One explanation for these results has been based on the importance animate objects have served over the course of our species' history. In the present set of experiments, we present stimuli, which could be perceived as animate, but with which our distant ancestors would have had no experience, and natural selection could have no direct pressure on their prioritization. In the first experiment, we compared LEGO® "people" with LEGO "nonpeople" in a change detection task. In a second experiment, we attempt to control the heterogeneity of the nonanimate objects by using LEGO blocks, matched in size and colour to LEGO people. In the third experiment, we occlude the faces of the LEGO people to control for facial pattern recognition. In the final 2 experiments, we attempt to obscure high-level categorical information processing of the stimuli by inverting and blurring the scenes. (PsycINFO Database Record

Developmental trajectories of form perception: A story of attention.

The developmental trajectories of selective and divided attention were examined in relation to the processing of hierarchically integrated stimuli. The participants included children in 4 age groups (6, 8, 10, and 12 years) and a group of young adults (24 years) who completed 2 computer-based attention tasks. In the selective attention task, the participants were instructed to attend to only 1 level of analysis and ignore the other. In the divided attention task, participants were told that the target could appear at either level, and the probability that a target would appear at either the global or local level was manipulated. For both of the tasks, distinct and qualitative developmental shifts were evident both between 6 and 8 years of age and between 8 and 10 years of age. Attention to the global form developed prior to, and may have been a prerequisite of, attention to the local form. These gains in attentional control occurred in terms of selective attention, sensitivity to the probability of bias, and relative efficiency in processing global and local targets. The clear developmental trajectory is consistent with the emergent role of voluntary attention in the processing of these types of stimuli.

One size does not fit all: older adults benefit from redundant text in multimedia instruction.

The multimedia design of presentations typically ignores that younger and older adults have varying cognitive strengths and weaknesses. We examined whether differential instructional design may enhance learning in these populations. Younger and older participants viewed one of three computer-based presentations: Audio only (narration), Redundant (audio narration with redundant text), or Complementary (audio narration with non-redundant text and images). Younger participants learned better when audio narration was paired with relevant images compared to when audio narration was paired with redundant text. However, older participants learned best when audio narration was paired with redundant text. Younger adults, who presumably have a higher working memory capacity (WMC), appear to benefit more from complementary information that may drive deeper conceptual processing. In contrast, older adults learn better from presentations that support redundant coding across modalities, which may help mitigate the effects of age-related decline in WMC. Additionally, several misconceptions of design quality appeared across age groups: both younger and older participants positively rated less effective designs. Findings suggest that one-size does not fit all, with older adults requiring unique multimedia design tailored to their cognitive abilities for effective learning.

Contextual control over selective attention: evidence from a two-target method.

Selective attention is generally studied with conflict tasks, using response time as the dependent measure. Here, we study the impact of selective attention to a first target, T1, presented simultaneously with a distractor, on the accuracy of subsequent encoding of a second target item, T2. This procedure produces an "attentional blink" (AB) effect much like that reported in other studies, and allowed us to study the influence of context on cognitive control with a novel method. In particular, we examined whether preparation to attend selectively to T1 had an impact on the selective encoding of T1 that would translate to report of T2. Preparation to attend selectively was manipulated by varying whether difficult selective attention T1 trials were presented in the context of other difficult selective attention T1 trials. The results revealed strong context effects of this nature, with smaller AB effects when difficult selective attention T1 trials were embedded in a context with many, rather than few, other difficult selective attention T1 trials. Further, the results suggest that both the trial-to-trial local context and the block-wide global context modulate performance in this task.

Exploring the role of the amplitude envelope in duration estimation.

A sound's duration provides important information about the event producing it. Although many of the sounds we hear every day are 'percussive' in nature (ie resulting from two objects impacting) and therefore exhibit decaying/damped amplitude envelopes, perceptual experiments frequently use tones synthesized with 'flat' or abruptly ending envelopes. Such sounds afford an estimation strategy involving calculating the elapsed time between tone onset and offset--a strategy that would be problematic for ecologically pervasive decaying sounds. Here we compare duration judgments for tones with percussive (ie gradually decaying) and flat (ie abruptly ending) amplitude envelopes, finding evidence for the use of different strategies. This result is discussed in terms of its implications for dominant theories and models of sensory perception that are often assessed using artificial sounds (ie 'flat tones') affording strategies that may not be optimal or even available for everyday listening.

Crossing the arms confuses the clocks: sensory feedback and the bimanual advantage.

The bimanual advantage refers to the finding that tapping with two fingers on opposite hands exhibits reduced timing variability, as compared with tapping with only one finger. Two leading theories propose that the bimanual advantage results from the addition of either sensory (i.e., enhanced feedback) or cognitive (i.e., multiple timekeeper) processes involved in timing. Given that crossing the arms impairs perception of tactile stimuli and modulates cortical activation following tactile stimulation, we investigated the role of crossing the arms in the bimanual advantage. Participants tapped unimanually or bimanually with their arms crossed or uncrossed on a tabletop or in the air. With arms crossed, we expected increased interval timing variance. Similarly, for air tapping, we expected reduced bimanual advantage, due to reduced sensory feedback. A significant bimanual advantage was observed for the uncrossed, but not the crossed posture in tabletop tapping. Furthermore, removing tactile feedback from taps eliminated the bimanual advantage for both postures. Together, these findings suggest that crossing the arms likely impairs integration of internal (i.e., effector-specific) and external (i.e., environment-specific) information and that this multisensory integration is crucial to reducing timing variability during repetitive coordinated bimanual tasks.

Space and time: an impact of spatial separation, apparent motion, and perceptual grouping on TOJ performance.

This study explored the effects of spacing and objecthood (ie grouping based on closure) on temporal order judgment (TOJ) with displays that either involved successive onset of the target stimuli, resulting in apparent motion (experiments 1 and 2), or included simultaneous onset but successive shortening of the stimuli, and therefore did not result in apparent motion (experiment 3). We found a robust effect of spatial separation whose nature depended on whether or not the display allowed the emergence of illusory motion. Specifically, with apparent motion TOJ was best with the smallest spacing, but without it TOJ was worst with the smallest spacing. Moreover, overall accuracy was better with, than without, apparent motion. A small effect of objecthood--poorer TOJ performance when the elements formed an object--emerged only when spacing was not manipulated. These findings suggest that different mechanisms mediate temporal processing when we have access to motion information than when we do not.