Human Illusion Research Articles

Monkeys overestimate connected arrays in a relative quantity task: A reverse connectedness illusion.

Humans and many other species show consistent patterns of responding when making relative quantity ("more or less") judgments of stimuli. This includes the well-established ratio effect that determines the degree of discriminability among sets of items according to Weber's Law. However, humans and other species also are susceptible to some errors in accurately representing quantity, and these illusions reflect important aspects of the relation of perception to quantity representation. One newly described illusion in humans is the connectedness illusion, in which arrays with items that are connected to each other tend to be underestimated relative to arrays without such connection. In this pre-registered report, we assessed whether this illusion occurred in other species, testing rhesus macaque monkeys and capuchin monkeys. Contrary to our pre-registered predictions, monkeys showed an opposite bias to humans, preferring to select arrays with connected items as being more numerous. Thus, monkeys do not show this illusion to the same extent as humans.

Seers who unmask illusion

As humanity seeks to redefine its relationships with technology, the earth and ultimate reality, the mystics can assist in discerning a way forward. How can we live at peace in a rapidly changing and technologically advancing world? Will these redefined relationships facilitate human flourishing or cause alienation? Twentieth century mystics Thomas Merton and Henri J. M. Nouwen believed that the conversation began with confronting illusion. The illusions human beings construct begin in the Self (with the false personas we create) but extend to the collectives we relate to. Merton and Nouwen were mystics and social critics, from a starting point of contemplation, representing ‘Christ, the challenger and disturber of human illusion.’ This article seeks to showcase their contribution while outlining some spiritual practices seekers might adopt to navigate our complex and constantly transforming milieu.

Pandemics, Power, and Conspiracy Theories

Pandemics, Power, and Conspiracy Theories

Exploring the Müller-Lyer illusion in a nonavian reptile (Pogona vitticeps).

Visual illusions have been widely used to compare visual perception among birds and mammals to assess whether animals interpret and alter visual inputs like humans, or if they detect them with little or no variability. Here, we investigated whether a nonavian reptile (Pogona vitticeps) perceives the Müller-Lyer illusion, an illusion that causes a misperception of the relative length of 2 line segments. We observed the animals' spontaneous tendency to choose the larger food quantity (the longer line). In test trials, animals received the same food quantity presented in a spatial arrangement eliciting the size illusion in humans; control trials presented them with 2 different-sized food portions. Bearded dragons significantly selected the larger food quantity in control trials, confirming that they maximized food intake. Group analysis revealed that in the illusory test trials, they preferentially selected the line length estimated as longer by human observers. Further control trials excluded the possibility that their choice was based on potential spatial bias related to the illusory pattern. Our study suggests that a nonavian reptile species has the capability to be sensitive to the Müller-Lyer illusion, raising the intriguing possibility that the perceptual mechanisms underlying size estimation might be similar across amniotes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Mechanism for analogous illusory motion perception in flies and humans

Visual motion detection is one of the most important computations performed by visual circuits. Yet, we perceive vivid illusory motion in stationary, periodic luminance gradients that contain no true motion. This illusion is shared by diverse vertebrate species, but theories proposed to explain this illusion have remained difficult to test. Here, we demonstrate that in the fruit fly Drosophila, the illusory motion percept is generated by unbalanced contributions of direction-selective neurons' responses to stationary edges. First, we found that flies, like humans, perceive sustained motion in the stationary gradients. The percept was abolished when the elementary motion detector neurons T4 and T5 were silenced. In vivo calcium imaging revealed that T4 and T5 neurons encode the location and polarity of stationary edges. Furthermore, our proposed mechanistic model allowed us to predictably manipulate both the magnitude and direction of the fly's illusory percept by selectively silencing either T4 or T5 neurons. Interestingly, human brains possess the same mechanistic ingredients that drive our model in flies. When we adapted human observers to moving light edges or dark edges, we could manipulate the magnitude and direction of their percepts as well, suggesting that mechanisms similar to the fly's may also underlie this illusion in humans. By taking a comparative approach that exploits Drosophila neurogenetics, our results provide a causal, mechanistic account for a long-known visual illusion. These results argue that this illusion arises from architectures for motion detection that are shared across phyla.

The Delboeuf illusion's bias in food choice of teleost fishes: an interspecific study

An optimal foraging strategy often requires identifying and choosing the larger amount of food in the presence of multiple options, in order to maximize food intake. Food quantity estimation frequently depends on the perceptual ability to segregate food from the surrounding background. In human and nonhuman animals, it has recently been shown that the perception of food size is affected by the size of the background on which food is presented, with a tendency to overestimate food items encircled by a small background. This perceptual bias resembles an illusory effect known as the Delboeuf illusion. We investigated whether this bias occurs in five fish species: zebrafish, Danio rerio, redtail splitfin, Xenotoca eiseni, angelfish, Pterophyllum scalare, Siamese fighting fish, Betta splendens, and three-spot gourami, Trichopodus trichopterus. In control trials, we observed their spontaneous preference for choosing the larger of two amounts of food. In test trials, two same-sized food amounts were presented on a small and a large plate, a pattern that causes the Delboeuf illusion in humans. Similarities in subjects’ choices between the five species were greater than differences, with a significant bias towards selecting the food amount on the large plate. This suggests the existence of a perceptual bias, although one operating in the opposite direction from that of humans, which might interfere with the accurate food size estimation necessary for an optimal foraging strategy.

Statistical inference of body representation in the macaque brain

The sense of one's own body is a pillar of self-consciousness and could be investigated by inducing human illusions of artificial objects as part of the self. Here, we present a nonhuman primate version of a rubber-hand illusion that allowed us to determine its computational and neuronal mechanisms. We implemented a video-based system in a reaching task in monkeys and combined a casual inference model to establish an objective and quantitative signature for the monkey's body representation. Similar to humans, monkeys were more likely to perceive an external object as part of the self when the dynamics (spatial disparity) and the features (shape and structure) of visual (V) input was closer to proprioceptive (P) signals. Neural signals in the monkey's premotor cortex reflected the strength of illusion and the likelihood of misattributing the illusory hand to oneself, thus, revealing a cortical representation of body ownership.

Organization of the Thermal Grill Illusion by Spinal Segments.

ObjectiveA common symptom of neuropathy is the misperception of heat and pain from cold stimuli. Similar cold allodynic sensations can be experimentally induced using the thermal grill illusion (TGI) in humans. It is currently unclear whether this interaction between thermosensory and nociceptive signals depends on spinal or supraspinal integration mechanisms. To address this issue, we developed a noninvasive protocol to assess thermosensory integration across spinal segments.MethodsWe leveraged anatomical knowledge regarding dermatomes and their spinal projections to investigate potential contributions of spinal integration to the TGI. We simultaneously stimulated a pair of skin locations on the arm or lower back using 1 cold (∼20°C) and 1 warm thermode (∼40°C). The 2 thermodes were always separated by a fixed physical distance on the skin, but elicited neural activity across a varying number of spinal segments, depending on which dermatomal boundaries the 2 stimuli spanned.ResultsParticipants consistently overestimated the actual cold temperature on the skin during combined cold and warm stimulation, confirming the TGI effect. The TGI was present when cold and warm stimuli were delivered within the same dermatome, or across dermatomes corresponding to adjacent spinal segments. In striking contrast, no TGI effect was found when cold and warm stimuli projected to nonadjacent spinal segments.InterpretationThese results demonstrate that the strength of the illusion is modulated by the segmental distance between cold and warm afferents. This suggests that both temperature perception and thermal–nociceptive interactions depend upon low‐level convergence mechanisms operating within a single spinal segment and its immediate neighbors. Ann Neurol 2018;84:463–472

Neuronal population mechanisms of lightness perception.

The way that humans and animals perceive the lightness of an object depends on its physical luminance as well as its surrounding context. While neuronal responses throughout the visual pathway are modulated by context, the relationship between neuronal responses and lightness perception is poorly understood. We searched for a neuronal mechanism of lightness by recording responses of neuronal populations in monkey primary visual cortex (V1) and area V4 to stimuli that produce a lightness illusion in humans, in which the lightness of a disk depends on the context in which it is embedded. We found that the way individual units encode the luminance (or equivalently for our stimuli, contrast) of the disk and its context is extremely heterogeneous. This motivated us to ask whether the population representation in either V1 or V4 satisfies three criteria: 1) disk luminance is represented with high fidelity, 2) the context surrounding the disk is also represented, and 3) the representations of disk luminance and context interact to create a representation of lightness that depends on these factors in a manner consistent with human psychophysical judgments of disk lightness. We found that populations of units in both V1 and V4 fulfill the first two criteria but that we cannot conclude that the two types of information in either area interact in a manner that clearly predicts human psychophysical measurements: the interpretation of our population measurements depends on how subsequent areas read out lightness from the population responses. NEW & NOTEWORTHY A core question in visual neuroscience is how the brain extracts stable representations of object properties from the retinal image. We searched for a neuronal mechanism of lightness perception by determining whether the responses of neuronal populations in primary visual cortex and area V4 could account for a lightness illusion measured using human psychophysics. Our results suggest that comparing psychophysics with population recordings will yield insight into neuronal mechanisms underlying a variety of perceptual phenomena.

Heading representations in primates are compressed by saccades

Perceptual illusions help to understand how sensory signals are decoded in the brain. Here we report that the opposite approach is also applicable, i.e., results from decoding neural activity from monkey extrastriate visual cortex correctly predict a hitherto unknown perceptual illusion in humans. We record neural activity from monkey medial superior temporal (MST) and ventral intraparietal (VIP) area during presentation of self-motion stimuli and concurrent reflexive eye movements. A heading-decoder performs veridically during slow eye movements. During fast eye movements (saccades), however, the decoder erroneously reports compression of heading toward straight ahead. Functional equivalents of macaque areas MST and VIP have been identified in humans, implying a perceptual correlate (illusion) of this perisaccadic decoding error. Indeed, a behavioral experiment in humans shows that perceived heading is perisaccadically compressed toward the direction of gaze. Response properties of primate areas MST and VIP are consistent with being the substrate of the newly described visual illusion.

March 2017: This Month in JoVE: Human Embryo Vitrification, Paper Microfluidic Devices, Virtual Hand/Face Illusions, and Quantification of Amyloid-Beta for Alzheimer's Diagnosis

Here's a look at what's coming up in the March 2017 issue of JoVE: The Journal of Visualized Experiments. As the start of spring brings new life, we begin the month investigating exciting new developments in embryo storage for in-vitro fertility treatment. In JoVE Developmental Biology, our authors present a modified technique for vitrification and preservation of human embryos. This aseptic technique uses all FDA-compliant materials including ionomeric resin embryo straws and sterile flexipettes, and allows fast, safe, and repeatable embryo storage independent of operator variation. In addition, with a greater than 95% embryo survival-rate the method contributes to excellent pregnancy outcomes. Paper cards...printers, it's all so 1990's, right? Well, our next video highlight might make you reconsider. In JoVE Bioengineering this month, our authors reveal 3-dimensional paper microfluidic devices for immunoassays. By patterning paper with hydrophobic barriers, the transfer of fluids can be controlled and directed. Stacking multiple layers of patterned paper creates sophisticated 3-D microfluidic networks that can be utilized in cheap and simple bioanalytical assays, such as the detection of Human Chorionic Gonadotriphin, or hCG - the pregnancy hormone. So don't throw out those old Valentine's Day cards yet - upcycle! In JoVE Medicine this month, our authors reveal an accurate procedure for quantifying the plaque-forming amyloid-beta protein in cerebral spinal fluid to provide diagnoses in suspected Alzheimer's cases. Current diagnosis is mostly based on mental state and cognitive testing, with some studies beginning to examine amyloid-beta levels, but this is hampered by variability and reproducibility issues. Here, our authors use a combination of solid-phase extraction and liquid chromatography tandem mass spectrometry to quantify amyloid-beta levels to a high degree of accuracy, quantifying the deposition of the protein in plaques in the brain and enhancing the power for accurate diagnoses. Our final video highlight this month comes from JoVE Behavior, and showcases a new technique to create human body illusions. Here, our authors demonstrate a computer-based virtual hand and face that move in synchrony with the operator's action, creating an illusion that the model is an extension of the participant's own body. This is a useful tool in the study of self-representation, and is an advance over traditional studies requiring demonstrators to mimic actions on participants in time with actions performed on a physical model body part. Ah, just one small step until I realize my dream of becoming a super-fast blue hedgehog. You've just had a sneak peek of the March 2017 issue of JoVE. Visit the website to see the full-length articles, plus many more, in JoVE: The Journal of Visualized Experiments.

Visual perception in domestic dogs: susceptibility to the Ebbinghaus-Titchener and Delboeuf illusions.

Susceptibility to geometrical visual illusions has been tested in a number of non-human animal species, providing important information about how these species perceive their environment. Considering their active role in human lives, visual illusion susceptibility was tested in domestic dogs (Canis familiaris). Using a two-choice simultaneous discrimination paradigm, eight dogs were trained to indicate which of two presented circles appeared largest. These circles were then embedded in three different illusory displays; a classical display of the Ebbinghaus-Titchener illusion; an illusory contour version of the Ebbinghaus-Titchener illusion; and the classical display of the Delboeuf illusion. Significant results were observed in both the classical and illusory contour versions of the Ebbinghaus-Titchener illusion, but not the Delboeuf illusion. However, this susceptibility was reversed from what is typically seen in humans and most mammals. Dogs consistently indicated that the target circle typically appearing larger in humans appeared smaller to them, and that the target circle typically appearing smaller in humans, appeared larger to them. We speculate that these results are best explained by assimilation theory rather than other visual cognitive theories explaining susceptibility to this illusion in humans. In this context, we argue that our findings appear to reflect higher-order conceptual processing in dogs that cannot be explained by accounts restricted to low-level mechanisms of early visual processing.

How Illusory Is the Solitaire Illusion? Assessing the Degree of Misperception of Numerosity in Adult Humans

The Solitaire illusion occurs when the spatial arrangement of items influences the subjective estimation of their quantity. Unlike other illusory phenomena frequently reported in humans and often also in non-human animals, evidence of the Solitaire illusion in species other than humans remains weak. However, before concluding that this perceptual bias affects quantity judgments differently in human and non-human animals, further investigations on the strength of the Solitaire illusion is required. To date, no study has assessed the exact misperception of numerosity generated by the Solitaire arrangement, and the possibility exists that the numerical effects generated by the illusion are too subtle to be detected by non-human animals. The present study investigated the strength of this illusion in adult humans. In a relative numerosity task, participants were required to select which array contained more blue items in the presence of two arrays made of identical blue and yellow items. Participants perceived the Solitaire illusion as predicted, overestimating the Solitaire array with centrally clustered blue items as more numerous than the Solitaire array with blue items on the perimeter. Their performance in the presence of the Solitaire array was similar to that observed in control trials with numerical ratios larger than 0.67, suggesting that the illusory array produces a substantial overestimation of the number of blue items in one array relative to the other. This aspect was more directly investigated in a numerosity identification task in which participants were required to estimate the number of blue items when single arrays were presented one at a time. In the presence of the Solitaire array, participants slightly overestimated the number of items when they were centrally located while they underestimated the number of items when those items were located on the perimeter. Items located on the perimeter were perceived to be 76% as numerous as centrally located items. The magnitude of misperception of numerosity reported here may represent a useful tool to help to understand whether non-human animals have different perceptual mechanisms or, instead, do not display adequate numerical abilities to spot the illusory difference generated in the Solitaire array.

Fat Face Illusion, or Jastrow Illusion with Faces, in Humans but not in Chimpanzees.

When two identical faces are aligned vertically, humans readily perceive the face at the bottom to be fatter than the top one. This phenomenon is called the fat face illusion. Furthermore, an apparent similarity has been pointed out between the fat face illusion and the Jastrow illusion. Recent studies have suggested the importance of facial contours and the role of basic-level processing of faces. In the present study, we directly compared the typical Jastrow illusion and fat face illusion in humans and chimpanzees using the same task. Both humans and chimpanzees clearly showed the Jastrow illusion, but only humans perceived the face at the bottom as fatter than the top. Although further examination is necessary, these results might reflect different processing levels of faces between the two species.

Derridean Blackmail in The Big Sleep : Allegorizing the Unfixable Mirages of Photography, Film and Criticism

Recent criticism has already shown that the notoriously unanswered plot questions of The Big Sleep elicit serious philosophical issues, including skepticism about the validity of interpretation itself. The film allegorizes the reason for this questioning in what Derrida calls the blackmail of photography--its coercive claim to represent objective truth. Blackmail arising from photography is the main plot premise of The Big Sleep, but it serves as a figure for the postal world of signs divorced from referents, finally epitomized in thel groundlessness of Marlowe's logic and final conclusions. Parallels are drawn between this Derridean world and Adorno's writings, in the light of Derrida's acknowledgement of their affinity. The phrase big sleep is gangster-slang for death, but this essay argues that it also refers to life, understood in the Buddhist sense of the human illusion of a waking or enlightened life.

English

The author makes an attempt to give arguments for ontological nature of sociocultural illusions. An accurate determination of sociocultural illusions is founded on the definitions of human illusions that were suggested by I. Kant. Experience of branching classification of sociocultural illusions is demonstrated.

Near-death experiences: heavenly insight or human illusion?

Near-death experiences: heavenly insight or human illusion?

Do rhesus monkeys (Macaca mulatta) perceive the Zöllner illusion?

A long-standing debate surrounds the issue of whether human and nonhuman animals share the same perceptual mechanisms. In humans, the Zöllner illusion occurs when two parallel lines appear to be convergent when oblique crosshatching lines are superimposed. Although one baboon study suggests that they too might perceive this illusion, the results of that study were unclear, whereas two recent studies suggest that birds see this illusion in the opposite direction from humans. It is currently unclear whether these mixed results are an artifact of the experimental design or reflect a peculiarity of birds' visual system or, instead, a wider phenomenon shared among nonhuman mammals. Here, we trained 6 monkeys to select the narrower of two gaps at the end of two convergent lines. Three different conditions were set up: control (no crosshatches), perpendicular (crosshatches not inducing the illusion), and Zöllner (crosshatches inducing the illusion in humans). During training, the degrees of convergence between the two lines ranged from 15° to 12°. Monkeys that reached the training criterion were tested with more difficult discriminations (11°-1°), including probe trials with parallel lines (0°). The results showed that monkeys perceived the Zöllner illusion in the same direction as humans. Comparison of these data with the data from bird studies points toward the existence of different orientation-tuned mechanisms between primate and nonprimate species.

"Rzodkiewki" Janusza Morgensterna

Marek Hendrykowski’s essay presents the importance of Janusz Morgenstern’s early short film Radishes made after Stalin’s death, in 1954 as a student work produced by Film School in Łódź. The main character, old worker Gruliński loses his clear hopes and human illusions. The pesimistic conclusion is closed further by the simultaneous description of the hero’s social image within a discourse of origins and the sacred which evacuates analysis of class conflict and sociological approach in the narrative of an “ordinary good man” brutally disturbed in his desires and works by the irruption and power of an omnipotent destructive stalinist “red tape” bureaucracy. The poetics of Radishes is deeply influenced by the style of an Italian neorealism, first of all by its famous masterpiece, Vittorio De Sica’s Umberto D. (1952).

Debating psychic experience: human potential or human illusion?

This book presents a provocative debate between parapsychological advocates who claim that Western science's worldview is incomplete, and counteradvocates who insist that parapsychological data is either spurious or can be explained by standard scientific principles. * Includes contributions from 14 scholars weighing in as advocates, counteradvocates, or contributors * 20 examples of original artwork by Dierdre Luzwick, a world-class surrealistic artist * The bibliography contains a reference list at the end of each contributor's section * A glossary of key terms used in the book is supplied