The Influence of Auditory Information on Visual Size Adaptation

PsySuite: An android application designed to perform multimodal psychophysical testing

In behavioral sciences, there is growing concern about the inflation of false-positive rates due to the amount of under-powered studies that have been shared in the past years. While problematic, having the possibility to recruit (lots of) participants (for a lot of time) is realistically not achievable for many research facilities. Factors that hinder the reaching of optimal sample sizes are, to name but a few, research costs, participants' availability and commitment, and logistics. We challenge these issues by introducing PsySuite, an Android app designed to foster a remote approach to multimodal behavioral testing. To validate PsySuite, we first evaluated its ability to generate stimuli appropriate to rigorous psychophysical testing, measuring both the app's accuracy (i.e., stimuli's onset, offset, and multimodal simultaneity) and precision (i.e., the stability of a given pattern across trials), using two different smartphone models. We then evaluated PsySuite's ability to replicate perceptual performances obtained using a classic psychophysical paradigm, comparing sample data collected with the app against those measured via a PC-based setup. Our results showed that PsySuite could accurately reproduce stimuli with a minimum duration of 7 ms, 17 ms, and 30 ms for the auditory, visual, and tactile modalities, respectively, and that perceptual performances obtained with PsySuite were consistent with the perceptual behavior observed using the classical setup. Combined with the high accessibility inherently supported by PsySuite, here we ought to share the app to further boost psychophysical research, aiming at setting it to a cheap, user-friendly, and portable level.

Size adaptation: Do you know it when you see it?

The visual system adapts to a wide range of visual features, from lower-level features like color and motion to higher-level features like causality and, perhaps, number. According to some, adaptation is a strictly perceptual phenomenon, such that the presence of adaptation licenses the claim that a feature is truly perceptual in nature. Given the theoretical importance of claims about adaptation, then, it is important to understand exactly when the visual system does and does not exhibit adaptation. Here, we take as a case study one specific kind of adaptation: visual adaptation to size. Supported by evidence from four experiments, we argue that, despite robust effects of size adaptation in the lab, (1) size adaptation effects are phenomenologically underwhelming (in some cases, hardly appreciable at all), (2) some effects of size adaptation appear contradictory, and difficult to explain given current theories of size adaptation, and (3) prior studies on size adaptation may have failed to isolate size as the adapted dimension. Ultimately, we argue that while there is evidence to license the claim that size adaptation is genuine, size adaptation is a puzzling and poorly understood phenomenon.

Tactile adaptation to orientation produces a robust tilt aftereffect and exhibits crossmodal transfer when tested in vision

Orientation processing is one of the most fundamental functions in both visual and somatosensory perception. Converging findings suggest that orientation processing in both modalities is closely linked: somatosensory neurons share a similar orientation organisation as visual neurons, and the visual cortex has been found to be heavily involved in tactile orientation perception. Hence, we hypothesized that somatosensation would exhibit a similar orientation adaptation effect, and this adaptation effect would be transferable between the two modalities, considering the above-mentioned connection. The tilt aftereffect (TAE) is a demonstration of orientation adaptation and is used widely in behavioural experiments to investigate orientation mechanisms in vision. By testing the classic TAE paradigm in both tactile and crossmodal orientation tasks between vision and touch, we were able to show that tactile perception of orientation shows a very robust TAE, similar to its visual counterpart. We further show that orientation adaptation in touch transfers to produce a TAE when tested in vision, but not vice versa. Additionally, when examining the test sequence following adaptation for serial effects, we observed another asymmetry between the two conditions where the visual test sequence displayed a repulsive intramodal serial dependence effect while the tactile test sequence exhibited an attractive serial dependence. These findings provide concrete evidence that vision and touch engage a similar orientation processing mechanism. However, the asymmetry in the crossmodal transfer of TAE and serial dependence points to a non-reciprocal connection between the two modalities, providing further insights into the underlying processing mechanism.

Perceptual Biases as the Side Effect of a Multisensory Adaptive System: Insights from Verticality and Self-Motion Perception

Perceptual biases can be interpreted as adverse consequences of optimal processes which otherwise improve system performance. The review presented here focuses on the investigation of inaccuracies in multisensory perception by focusing on the perception of verticality and self-motion, where the vestibular sensory modality has a prominent role. Perception of verticality indicates how the system processes gravity. Thus, it represents an indirect measurement of vestibular perception. Head tilts can lead to biases in perceived verticality, interpreted as the influence of a vestibular prior set at the most common orientation relative to gravity (i.e., upright), useful for improving precision when upright (e.g., fall avoidance). Studies on the perception of verticality across development and in the presence of blindness show that prior acquisition is mediated by visual experience, thus unveiling the fundamental role of visuo-vestibular interconnections across development. Such multisensory interactions can be behaviorally tested with cross-modal aftereffect paradigms which test whether adaptation in one sensory modality induces biases in another, eventually revealing an interconnection between the tested sensory modalities. Such phenomena indicate the presence of multisensory neural mechanisms that constantly function to calibrate self-motion dedicated sensory modalities with each other as well as with the environment. Thus, biases in vestibular perception reveal how the brain optimally adapts to environmental requests, such as spatial navigation and steady changes in the surroundings.

The Role of Temporal and Spatial Attention in Size Adaptation

One of the most important tasks for the visual system is to construct an internal representation of the spatial properties of objects, including their size. Size perception includes a combination of bottom-up (retinal inputs) and top-down (e.g., expectations) information, which makes the estimates of object size malleable and susceptible to numerous contextual cues. For example, it has been shown that size perception is prone to adaptation: brief previous presentations of larger or smaller adapting stimuli at the same region of space changes the perceived size of a subsequent test stimulus. Large adapting stimuli cause the test to appear smaller than its veridical size and vice versa. Here, we investigated whether size adaptation is susceptible to attentional modulation. First, we measured the magnitude of adaptation aftereffects for a size discrimination task. Then, we compared these aftereffects (on average 15–20%) with those measured while participants were engaged, during the adaptation phase, in one of the two highly demanding central visual tasks: Multiple Object Tracking (MOT) or Rapid Serial Visual Presentation (RSVP). Our results indicate that deploying visual attention away from the adapters did not significantly affect the distortions of perceived size induced by adaptation, with accuracy and precision in the discrimination task being almost identical in all experimental conditions. Taken together, these results suggest that visual attention does not play a key role in size adaptation, in line with the idea that this phenomenon can be accounted for by local gain control mechanisms within area V1.

Visual and Auditory Information During Decision Making in Sport

In 2 experiments, the authors investigated the effects of bimodal integration in a sport-specific task. Beach volleyball players were required to make a tactical decision, responding either verbally or via a motor response, after being presented with visual, auditory, or both kinds of stimuli in a beach volleyball scenario. In Experiment 1, players made the correct decision in a game situation more often when visual and auditory information were congruent than in trials in which they experienced only one of the modalities or incongruent information. Decision-making accuracy was greater when motor, rather than verbal, responses were given. Experiment 2 replicated this congruence effect using different stimulus material and showed a decreasing effect of visual stimulation on decision making as a function of shorter visual stimulus durations. In conclusion, this study shows that bimodal integration of congruent visual and auditory information results in more accurate decision making in sport than unimodal information.

Coarse to Fine Audio-Visual Size Correspondences Develop During Primary School Age

Developmental studies have shown that children can associate visual size with non-visual and apparently unrelated stimuli, such as pure tone frequencies. Most research to date has focused on audio-visual size associations by showing that children can associate low pure tone frequencies with large objects, and high pure tone frequencies with small objects. Researchers relate these findings to coarser association, i.e., less precise associations for which binary categories of stimuli are used such as in the case of low versus high frequencies and large versus small visual stimuli. This study investigates how finer, more precise, crossmodal audio-visual associations develop during primary school age (from 6 to 11 years old). To unveil such patterns, we took advantage of a range of auditory pure tones and tested how primary school children match sounds with visually presented shapes. We tested 66 children (6-11 years old) in an audio-visual matching task involving a range of pure tone frequencies. Visual stimuli were circles or angles of different sizes. We asked participants to indicate the shape matching the sound. All children associated large objects/angles with low pitch, and small objects/angles with high pitch sounds. Interestingly, older children made greater use of intermediate visual sizes to provide their responses. Indeed, audio-visual associations for finer differences between stimulus features such as size and pure tone frequencies, may develop later depending on the maturation of supramodal size perception processes. Considering our results, we suggest that audio-visual size correspondences can be used for educational purposes by aiding the discrimination of sizes, including angles of different aperture. Moreover, their use should be shaped according to children's specific developmental stage.

Multisensory Interactive Technologies for Primary Education: From Science to Technology

While technology is increasingly used in the classroom, we observe at the same time that making teachers and students accept it is more difficult than expected. In this work, we focus on multisensory technologies and we argue that the intersection between current challenges in pedagogical practices and recent scientific evidence opens novel opportunities for these technologies to bring a significant benefit to the learning process. In our view, multisensory technologies are ideal for effectively supporting an embodied and enactive pedagogical approach exploiting the best-suited sensory modality to teach a concept at school. This represents a great opportunity for designing technologies, which are both grounded on robust scientific evidence and tailored to the actual needs of teachers and students. Based on our experience in technology-enhanced learning projects, we propose six golden rules we deem important for catching this opportunity and fully exploiting it.