Visual Perception of Apparent Motion Abides by Minimization Principles of Geometry

Apparent motion is a robust perceptual phenomenon in which observers perceive a stimulus traversing the vacant visual space between two flashed stimuli. Although it is known that the “filling-in” of apparent motion favors the simplest and most economical path, the interpolative computations remain poorly understood. Here, we tested whether the perception of apparent motion is best characterized by Newtonian physics or kinematic geometry. Participants completed a target detection task while Pacmen- shaped objects were presented in succession to create the perception of apparent motion. We found that target detection was impaired when apparent motion, as predicted by kinematic geometry, not Newtonian physics, obstructed the target’s location. Our findings shed light on the computations employed by the visual system, suggesting specifically that the “filling-in” perception of apparent motion may be dominated by kinematic geometry, not Newtonian physics.

The McGurk Effect In Relation to Musicians' Abilities

The original study of the McGurk Effect, a perceptual phenomenon caused by contradictory audiovisual stimuli fusing together to create the illusion of a third sound, was carried out by psychologists McGurk and MacDonald in 1976. The results of early experiments displayed that observers used both auditory and visual signals while being spoken to, auditory signals being the sound waves entering their ears, and visual signals being how the speaker moved his face while pronouncing a word. When conflicting signals are given, a third sound is perceived, as the brain is disoriented from the different signals. The idea that musicians have superior audiovisual cortexes have led some to speculate if musicians are as susceptible to the McGurk Effect as non-musicians. To research the susceptibility of musicians to the McGurk Effect, the experiment conducted included a total of 40 subjects, 20 musicians and 20 non-musicians. The subjects were played a control video of a speaker saying “ga” and were then presented with four audiovisually incongruent videos, all containing a speaker mouthing the word “ga” with the audio recording of the speaker saying “ba” dubbed on. Two main 2x2 Chi Square tests and fifteen secondary 2x2 Chi Squares tests were run in total. The two main tests, which compared the amount of McGurk interpretations to either audio or visual interpretations, both produced a p-value of <.0005. Upon further research, 25.7% of musicians reported a McGurk interpretation, as opposed to 52.2% of non-musicians, which implied that musicians are less susceptible to the McGurk effect.

The Plausibility Paradox for Resized Users in Virtual Environments

This paper identifies and confirms a perceptual phenomenon: when users interact with simulated objects in a virtual environment where the users’ scale deviates greatly from normal, there is a mismatch between the object physics they consider realistic and the object physics that would be correct at that scale. We report the findings of two studies investigating the relationship between perceived realism and a physically accurate approximation of reality in a virtual reality experience in which the user has been scaled by a factor of ten. Study 1 investigated perception of physics when scaled-down by a factor of ten, whereas Study 2 focused on enlargement by a similar amount. Studies were carried out as within-subjects experiments in which a total of 84 subjects performed simple interaction tasks with objects under two different physics simulation conditions. In the true physics condition, the objects, when dropped and thrown, behaved accurately according to the physics that would be correct at that either reduced or enlarged scale in the real world. In the movie physics condition, the objects behaved in a similar manner as they would if no scaling of the user had occurred. We found that a significant majority of the users considered the movie physics condition to be the more realistic one. However, at enlarged scale, many users considered true physics to match their expectations even if they ultimately believed movie physics to be the realistic condition. We argue that our findings have implications for many virtual reality and telepresence applications involving operation with simulated or physical objects in abnormal and especially small scales.

The role of cognitive factors and personality traits in the perception of illusory self-motion (vection)

Vection is a perceptual phenomenon that describes the visually induced subjective sensation of self-motion in the absence of physical motion. Previous research has discussed the potential involvement of top-down cognitive mechanisms on vection. Here, we quantified how cognitive manipulations such as contextual information (i.e., expectation) and plausibility (i.e., chair configuration) alter vection. We also explored how individual traits such as field dependence, depersonalization, anxiety, and social desirability might be related to vection. Fifty-one healthy adults were exposed to an optic flow stimulus that consisted of horizontally moving black-and-white bars presented on three adjacent monitors to generate circular vection. Participants were divided into three groups and given experimental instructions designed to induce either strong, weak, or no expectation with regard to the intensity of vection. In addition, the configuration of the chair (rotatable or fixed) was modified during the experiment. Vection onset time, duration, and intensity were recorded. Results showed that expectation altered vection intensity, but only when the chair was in the rotatable configuration. Positive correlations for vection measures with field dependence and depersonalization, but no sex-related effects were found. Our results show that vection can be altered by cognitive factors and that individual traits can affect the perception of vection, suggesting that vection is not a purely perceptual phenomenon, but can also be affected by top-down mechanisms.

Pareidolia and the Pitfalls of Subjective Interpretation of Ambiguous Images in Art History

In art history, we sometimes discover hidden images within a picture and conduct a subjective introspective analysis of the motivation behind these images. The author argues that many such highly ambiguous hidden images are better explained by the pareidolia phenomenon: the tendency to find patterns in random stimuli. The arguments brought forth by Sidney Geist and Dario Gamboni illustrate the pitfalls and controversy of subjective visual analysis and how a perceptual phenomenon can mislead our conclusions. This article proposes that this controversy can be approached by establishing pictorial intent: Did the artist deliberately paint the hidden image, or is it merely a perceptual artifact?

An online headphone screening test based on dichotic pitch

Online experimental platforms can be used as an alternative to, or complement, lab-based research. However, when conducting auditory experiments via online methods, the researcher has limited control over the participants’ listening environment. We offer a new method to probe one aspect of that environment, headphone use. Headphones not only provide better control of sound presentation but can also “shield” the listener from background noise. Here we present a rapid (< 3 min) headphone screening test based on Huggins Pitch (HP), a perceptual phenomenon that can only be detected when stimuli are presented dichotically. We validate this test using a cohort of “Trusted” online participants who completed the test using both headphones and loudspeakers. The same participants were also used to test an existing headphone test (AP test; Woods et al., 2017, Attention Perception Psychophysics). We demonstrate that compared to the AP test, the HP test has a higher selectivity for headphone users, rendering it as a compelling alternative to existing methods. Overall, the new HP test correctly detects 80% of headphone users and has a false-positive rate of 20%. Moreover, we demonstrate that combining the HP test with an additional test–either the AP test or an alternative based on a beat test (BT)–can lower the false-positive rate to ~ 7%. This should be useful in situations where headphone use is particularly critical (e.g., dichotic or spatial manipulations). Code for implementing the new tests is publicly available in JavaScript and through Gorilla (gorilla.sc).

A Potential Case of Inattentional Blindness in a Police-Pursuit Collision

The perceptual phenomenon of “inattentional blindness” has been widely acknowledged in the scientific literature for 30 years. In addition to the laboratory-based examples, real-life examples appear in the literature. This paper provides a case study where a deputy sheriff’s patrol car collided with a fleeing motorcyclist – with unique circumstances – as recorded on in-car-camera (ICC) videos. Although the motorcyclist brought suit alleging the deputy intentionally collided with him, the deputy reported that he first noticed another deputy running after the motorcyclist prior to seeing the fleeing motorcyclist. However, the ICC video from the involved deputy’s patrol car strongly supports the motorcyclist was visible from the deputy’s perspective before the on-foot deputy appeared. The facts of this incident are compared to the widely accepted characteristics of inattentional blindness in exploring whether that perceptual phenomenon may have been at play in this case.

Contrasting a Misinterpretation of the Reverse Contrast

The reverse contrast is a perceptual phenomenon in which the effect of the classical simultaneous lightness contrast is reversed. In classic simultaneous lightness contrast configurations, a gray surrounded by black is perceived lighter than an identical gray surrounded by white, but in the reverse contrast configurations, the perceptual outcome is the opposite: a gray surrounded by black appears darker than the same gray surrounded by white. The explanation provided for the reverse contrast (by different authors) is the belongingness of the gray targets to a more complex configuration. Different configurations show the occurrence of these phenomena; however, the factors determining this effect are not always the same. In particular, some configurations are based on both belongingness and assimilation, while one configuration is based only on belongingness. The evidence that different factors determine the reverse contrast is crucial for future research dealing with achromatic color perception and, in particular, with lightness induction phenomena.

The double life of language systems: Modelling sonority with complementary symbol and signal based models

Sonority is a fundamental notion in phonetics and phonology, central to many descriptions of the syllable and evidently useful as a predictor of phonotactics (i.e., the propensity of different consonants and vowels to combine via concatenation). Although widely-accepted, sonority lacks a clear basis in speech articulation or perception, and traditional sonority principles exhibit gaps in empirical coverage, while they are also not designed to be compatible with general cognitive capacities. Against the backdrop of traditional sonority accounts, which have been exclusively based on discrete and symbolic machinery to model sonority, we propose an incorporation of symbol-based and signal-based models to adequately account for sonority with two complementary models. We claim that sonority is primarily a perceptual phenomenon related to the strength and quality of pitch perception, postulating a universal drive to optimize syllables as pitch-bearing units. We suggest a measurable acoustic correlate for sonority in terms of periodic energy, and we provide a novel principle that can account for syllabic well-formedness based on principles of competition in real-time; the Nucleus Attraction Principle (NAP). We present two perception experiments that test our two NAP-based models against four traditional sonority models and we use a Bayesian data analysis approach to test and compare the different sonority models. We show that our two NAP models retain the highest degree of complementarity while one of them is clearly superior to all the other models we tested. We interpret the results as providing strong support for our proposals: (i) the designation of periodic energy as sonority's correlate; (ii) the incorporation of continuity in phonological models, and; (iii) the dual-model strategy that separates and integrates symbol-based top-down processes and signal-based bottom-up processes.