Effects of Symmetry and Apparent Distance in a Parasagittal-Mirror Variant of the Rubber Hand Illusion Paradigm.

When I see my face in a mirror, its apparent position (behind the glass) is not one that my own face could be in. I accept the face I see as my own because I have an implicit understanding of how mirrors work. The situation is different if I look at the reflection of my right hand in a parasagittal mirror (parallel to body midline) when my left hand is hidden behind the mirror. It is as if I were looking through a window at my own left hand. The experience of body ownership has been investigated using rubber hand illusion (RHI) paradigms, and several studies have demonstrated ownership of a rubber hand viewed in a frontal mirror. Our "proof of concept" study was the first to combine use of a parasagittal mirror and synchronous stroking of both a prosthetic hand (viewed in the mirror) and the participant's hand, with a manipulation of distance between the hands. The strength of the RHI elicited by our parasagittal-mirror paradigm depended not on physical distance between the hands (30, 45, or 60 cm) but on apparent distance between the prosthetic hand (viewed in the mirror) and the participant's hand. This apparent distance was reduced to zero when the prosthetic hand and participant's hand were arranged symmetrically (e.g., 30 cm in front of and behind the mirror). Thus, the parasagittal-mirror paradigm may provide a distinctive way to assess whether competition for ownership depends on spatial separation between the prosthetic hand and the participant's hand.

Autistic traits and loneliness in autism are associated with increased tendencies to anthropomorphise.

Anthropomorphism-the attribution of human qualities to non-human objects-is believed to be a natural tendency which may serve several adaptive functions. One possibility is that anthropomorphism provides an egocentric heuristic by which we can understand the world. It may also be a strategy for reducing our subjective sense of loneliness. However, not all humans exhibit the same propensity to anthropomorphise. Recent findings suggest that autistic individuals may be more likely to anthropomorphise than non-autistic individuals. In Study 1, we conducted a large-scale survey of autistic traits and dispositional anthropomorphism in the general population (n = 870). We found that individuals who reported having more autistic traits had an increased dispositional tendency to anthropomorphise non-human entities. In Study 2, we more closely examined variation in anthropomorphism tendencies in a sample of autistic adults (n = 90) to better understand what might drive increased anthropomorphism in this population. We found that those with greater anthropomorphism tendencies experienced greater levels of self-reported loneliness. We propose that increased anthropomorphism might reflect reduced opportunities for social connection for autistic people and those with more autistic traits.

Hand-Foot Coupling: An Advantage for Crossed Legs.

It is difficult to perform distinct, simultaneous motor actions with the ipsilateral hand and foot; for example, clockwise circles with the right hand and counter-clockwise circles with the right foot. By chance, we discovered that this hand-foot coupling task is easier when seated with legs crossed. We consider various explanations. First, that there are reduced demands on the contralateral hemisphere when the motor programme of the right foot is executed on the left side of the body. Second, that the legs-crossed scenario is easier because movements are symmetrical with respect to body midline. By considering related motor actions, we conclude that neither of these explanations provides a full account. Thus, we suggest a third explanation, which is that coupling effects are reduced by virtue of increased postural stability and reduced anticipatory postural adjustments.

A Friendly Article: The Qualitative Investigation of Anthropomorphism in Autistic and Nonautistic Adults.

Background: Anthropomorphism is the attribution of human characteristics to nonhuman agents. This common tendency is thought to be driven by a heightened motivation for social connection and may therefore be expected to be reduced in autistic individuals given that this group has been claimed to demonstrate reduced social motivation in some settings. However, the subject of anthropomorphism in autism has not been studied extensively, and online forums, autobiographical accounts, and recent research on the topic suggest that, contrary to this expectation, anthropomorphism is commonly experienced by autistic individuals. Methods: We conducted semi-structured interviews with eight autistic and eight nonautistic adults, all who reported a tendency to anthropomorphize. We recorded, transcribed, and analyzed the interviews according to the thematic analysis framework with the objective of identifying similarities and differences in the lived experiences of anthropomorphism in autistic and nonautistic individuals. Results: Individuals in both groups described anthropomorphism as comforting, promoting a sense of safety and friendship with, and feelings of empathy and sympathy toward, nonhuman agents. Autistic individuals stressed the important role anthropomorphized agents played in their life, particularly when growing up: easing loneliness and helping develop an understanding of emotions and relationships. Participants also expressed negative aspects of the phenomenon, with both autistic and nonautistic individuals worrying about anthropomorphized agents' feelings and well-being. For some individuals, such thoughts and feelings caused distress and were experienced as intrusive due to their involuntary nature. Conclusions: Autistic and nonautistic adults showed very similar anthropomorphic patterns. Although preliminary in nature, our findings highlight characteristics of anthropomorphic experiences for autistic and nonautistic individuals, furthering our understanding of individual differences in social cognition. By illustrating the important role nonhuman agents may play in the lives of autistic individuals, our findings may also guide future research and practice. Lay summary: Why was this study done?: 'Anthropomorphism' is when you feel that non-human items have human characteristics, for example if you experience plants, animals, or household objects as having thoughts or feelings. Anthropomorphism is experienced by many people in many different ways. Researchers think it might happen when people have a strong desire for social connection. This has led some to suggest that autistic people will be less likely to anthropomorphise due to difficulties in social understanding and motivation. However, researchers have not examined this directly, and our prior research, together with comments in online forums and autobiographical accounts, indicated that autistic individuals may experience a special relationship with non-human items.What was the purpose of this study?: The purpose of the study was to speak directly to people who anthropomorphise and hear about their experiences. We could then compare patterns of anthropomorphism between autistic and non-autistic adults.What did the researchers do?: We interviewed 16 adults (8 autistic and 8 non-autistic) who told us they anthropomorphised, and asked about their personal experiences of anthropomorphism.What were the results of the study?: Autistic and non-autistic adults described very similar experiences of anthropomorphism. People in both groups described anthropomorphism as comforting, and said that it gave them a sense of safety and friendship. They also cared for, and experienced feelings of empathy toward, anthropomorphised items. Individuals in both groups worried about anthropomorphised items' feelings and well-being and this caused some people considerable distress. Autistic individuals stressed the important role anthropomorphised items played in their life, particularly when growing up: reducing loneliness and helping them develop an understanding of emotions and relationships.What do these findings add to what was already known?: Our findings show that there are many similarities in the experiences of anthropomorphism in autistic and non-autistic adults. The findings also show how, for some autistic adults, anthropomorphism was helpful in developing relationships with other people.What are potential weaknesses in the study?: The small number of participants means that we do not know whether the findings would apply to all people who experience anthropomorphism.How will these findings help autistic adults now or in the future?: By showing the various ways in which autistic individuals attach social meanings (such as feelings of caring or friendship) to anthropomorphised items, our findings add to a growing number of studies which challenge the commonly-held assumption that autistic individuals are less motivated to make social connections. Our work shows that autistic individuals may be highly motivated to connect socially, and that meaningful social connections and expressions of empathy need not be limited to human beings.

Object personification in autism: This paper will be very sad if you don't read it.

Object personification is the attribution of human characteristics to non-human agents. In online forums, autistic individuals commonly report experiencing this phenomenon. Given that approximately half of all autistic individuals experience difficulties identifying their own emotions, the suggestion that object personification may be a feature of autism seems almost paradoxical. Why would a person experience sympathy for objects, when they struggle to understand and verbalise the emotions of other people as well as their own? An online survey was used to assess tendency for personification in 87 autistic and 263 non-autistic adults. Together, our results indicate that object personification occurs commonly among autistic individuals, and perhaps more often (and later in life) than in the general population. Given that in many cases, autistic people report their personification experiences as distressing, it is important to consider the reasons for the increased personification and identify structures for support.

"17" is odd and "seventeen" is even: Meaning and physical form in stimulus-parity synaesthesia.

For individuals with stimulus-parity synaesthesia, eliciting stimuli (e.g., shapes, numbers, letters, colours) trigger a compelling feeling of oddness or evenness. Given that (a) many inducers are conceptual and (b) parity is itself a conceptual property, one questions whether stimulus-parity synaesthesia will be a categorically higher subtype, such that the conceptual properties of stimuli will be crucial in determining parity. We explore this question as it applies to Synaesthete R, one of only two stimulus-parity synaesthetes known to the contemporary literature. In Experiments 1 and 2, we examine whether parity is tied to concepts or percepts, asking, for example, whether a rectangle is even regardless of whether it is presented as an image or a word. Our results indicate that the parity of shapes (words and images), numbers (words, digits, and Roman numerals), and letters (lowercase and uppercase) differs according to the stimulus format, supporting a perceptual explanation. In Experiment 3, we examine the parity of colour stimuli, showing a systematic relationship between the measurable physical properties of hue, saturation, and lightness and synaesthetic parity. Despite the conceptual nature of inducers and concurrents, for Synaesthete R, stimulus-parity synaesthesia is a lower subtype; perceptual properties of stimuli determine parity.

Inattentional blindness on the full-attention trial: Are we throwing out the baby with the bathwater?

When attention is otherwise engaged, observers may experience inattentional blindness, failing to notice objects or events that are presented in plain sight. In an inattentional blindness experiment, an unexpectedstimulus ispresented alongside primary-task stimuli, and its detection is probed. We evaluate a criterion that is commonly used to exclude observers from the data analysis. On the final experimental trial, observers do not perform the primary task, but instead look for anything new. Observers who fail to report the unexpected stimulus on thisfull-attention trialare excluded. On the basis of 4 hypothetical experiments and a review of 128 actual experiments from the literature, we demonstrate some potentially problematic consequences of implementing the full-attention-trial exclusion criterion. Excluded observers may cluster in experimental conditions and the exclusion criterion may lead researchers to understate the pervasiveness of inattentional blindness. It may even render usblindto inattentional blindness on the full-attention trial.

Automaticity in Stimulus-Parity Synaesthesia.

Automaticity is a defining characteristic of synaesthesia. Here, we assess for automaticity in stimulus-parity synaesthesia; a subtype that has been documented only 3 times in the literature. Synaesthete R experiences many (nonnumerical) stimuli as being odd or even. She described a toy shape-sorter, which paired odd shapes with even colour slots (and vice versa) and relayed difficulties with the incongruency created by this simple toy. Inspired by this anecdote, we devised a computerised task in which Synaesthete R (and 10 control participants) indicated the location of a target shape, which was presented on a coloured bar. Synaesthete R (but not control participants) was faster to report the location of target shapes presented on colours of congruent synaesthetic parity, relative to target shapes presented on colours of incongruent synaesthetic parity. These results constitute the first objective demonstration as to the automatic nature of associations in stimulus-parity synaesthesia.

Feeling Touch Through Glass: A Modified Rubber Hand Paradigm.

A variation on the rubber hand paradigm creates a striking illusion in which it seems to the participant that she or he is feeling touch through glass. This illusion provides insight about how individuals make use of predictive signals for integrating vision and touch.

Théodore Flournoy on synesthetic personification.

In 1893, Théodore Flournoy published a landmark book on synesthesia - Des phénomènes de synopsie [Of Synoptic Phenomena]. The book presented a pioneering chapter on synesthetic personification, including numerous striking case examples, and it is frequently cited by twenty-first-century researchers as providing some of the earliest examples of the phenomenon. Flournoy employed a broad definition of personification - the representation of stimuli as concrete and specific individuals or inanimate objects. This definition encompassed a more extensive set of phenomena than the definition used by researchers today and was illustrated by cases that would fall outside of contemporary subtypes of synesthetic personification. Yet, Flournoy's seminal work remains unavailable in English, and the extent of the phenomenon that he described has not been discussed in the contemporary literature. We provide an unabridged translation of Flournoy's chapter "Des personnifications" ["Of Personifications"].

Two Left Hands, Ten Interlaced Fingers: A New Rubber Hand Illusion.

A variation on the rubber hand paradigm elicits an illusion in which the participant's sense of body ownership can switch back and forth between two viewed prosthetic hands. The interlaced fingers paradigm involves three prosthetic left hands: Two are positioned in full view of the participant, with their fingers interlaced, and the fingers of a third prosthetic hand are interlaced with the fingers of the participant's left hand, which is hidden from view. The examiner alternates brushstrokes to the two viewed prosthetic hands, while administering synchronous brushstrokes to the participant's hidden hand. Most participants experience ownership for the prosthetic hand that is being stroked at a given moment.

The nonvisual illusion of self-touch: Misaligned hands and anatomical implausibility.

The self-touch illusion is elicited when the participant (with eyes closed) administers brushstrokes to a prosthetic hand while the examiner administers synchronous brushstrokes to the participant's other (receptive) hand. In three experiments we investigated the effects of misalignment on the self-touch illusion. In experiment 1 we manipulated alignment (0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees) of the prosthetic hand relative to the participant's receptive hand. The illusion was equally strong at 0 degrees and 45 degrees: the two conditions in which the prosthetic hand was in an anatomically plausible orientation. To investigate whether the illusion was diminished at 90 degrees (and beyond) by anatomical implausibility rather than by misalignment, in experiment 2 hand positioning was changed. The illusion was equally strong at 0 degrees, 45 degrees, and 90 degrees, but diminished at 135 degrees despite the prosthetic hand now being in an anatomically plausible orientation. Thus the illusion is diminished with misalignment of 135 degrees, irrespective of anatomical plausibility. Having demonstrated that the illusion was equally strong with the hands aligned (0 degrees) or misaligned by 45 degrees, in experiment 3 we demonstrated that participants did not detect a 45 degrees misalignment. Large degrees of misalignment prevent a compelling experience of the self-touch illusion, and the self-touch illusion prevents detection of small degrees of misalignment.

The no-touch rubber hand paradigm and mirror-touch sensation: Support for the self-other theory of mirror-touch synesthesia.

We thoroughly enjoyed Ward and Banissy's Discussion Paper on mirror-touch synesthesia. The authors contrast two theories for explaining this phenomenon-the Threshold Theory and their Self-Other Theory. Ward and Banissy note that the Self-Other Theory garners support from studies that have tested individuals with mirror-touch synesthesia using the rubber hand paradigm. In this Commentary, we provide further support for the Self-Other Theory by drawing on findings from control participants without mirror-touch synesthesia tested with two different no-touch rubber hand paradigms-one paradigm makes it easier while the other makes it more difficult to make the self-other distinction.

Stimulus-parity synaesthesia versus stimulus-dichotomy synaesthesia: Odd, even or something else?

In stimulus-parity synaesthesia, a range of stimuli-for example, letters, numbers, weekdays, months, and colours (the inducers)-elicit an automatic feeling of oddness or evenness (the concurrent). This phenomenon was first described by Théodore Flournoy in 1893, and has only recently been "rediscovered." Here, we describe an individual who experiences a comparable phenomenon, but uses the labels negative and positive rather than odd and even. Stimulus-parity synaesthesia may be broader than first supposed, and it is important that assessments are sensitive to this breadth.

A new method for assessing self-touch enhancement of the foot in stroke patients with mobility problems.

Patient NG is the first reported case of lower-limb 'self-touch enhancement' following stroke. Mobility problems prevented NG from reaching to touch her foot, thus we used a self-touch rubber-hand paradigm to mimic the conditions of self-administered touch. With vision precluded, NG administered stimulation to a prosthetic limb while the Examiner administered synchronous stimulation to NG's affected left foot. NG detected all stimulation administered with our self-touch paradigm, whereas in the control condition (with NG not involved in administering stimulation), NG had failed to detect one-third of Examiner-administered stimulation. When mobility problems are a barrier to investigating self-touch enhancement, the self-touch paradigm can be used to demonstrate residual tactile sensation following stroke.

Spatial limits on the nonvisual self-touch illusion and the visual rubber hand illusion: subjective experience of the illusion and proprioceptive drift.

The nonvisual self-touch rubber hand paradigm elicits the compelling illusion that one is touching one's own hand even though the two hands are not in contact. In four experiments, we investigated spatial limits of distance (15 cm, 30 cm, 45 cm, 60 cm) and alignment (0°, 90° anti-clockwise) on the nonvisual self-touch illusion and the well-known visual rubber hand illusion. Common procedures (synchronous and asynchronous stimulation administered for 60s with the prosthetic hand at body midline) and common assessment methods were used. Subjective experience of the illusion was assessed by agreement ratings for statements on a questionnaire and time of illusion onset. The nonvisual self-touch illusion was diminished though never abolished by distance and alignment manipulations, whereas the visual rubber hand illusion was more robust against these manipulations. We assessed proprioceptive drift, and implications of a double dissociation between subjective experience of the illusion and proprioceptive drift are discussed.

When you fail to see what you were told to look for: inattentional blindness and task instructions.

Inattentional blindness studies have shown that an unexpected object may go unnoticed if it does not share the property specified in the task instructions. Our aim was to demonstrate that observers develop an attentional set for a property not specified in the task instructions if it allows easier performance of the primary task. Three experiments were conducted using a dynamic selective-looking paradigm. Stimuli comprised four black squares and four white diamonds, so that shape and colour varied together. Task instructions specified shape but observers developed an attentional set for colour, because we made the black-white discrimination easier than the square-diamond discrimination. None of the observers instructed to count bounces by squares reported an unexpected white square, whereas two-thirds of observers instructed to count bounces by diamonds did report the white square. When attentional set departs from task instructions, you may fail to see what you were told to look for.

A sensational illusion: vision-touch synaesthesia and the rubber hand paradigm.

For individuals with vision-touch synaesthesia, the sight of touch on another person elicits synaesthetic tactile sensation on the observer's own body. Here we used the traditional rubber hand paradigm (Botvinick and Cohen, 1998) and a no-touch rubber hand paradigm to investigate and to authenticate synaesthetic tactile sensation. In the traditional rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner while the participant's hand - hidden from view - is also touched by the Examiner. Synchronous stimulation of the prosthetic hand and the participant's hidden hand elicits the rubber hand illusion. It may seem to the participant that she is feeling touch at the location of the viewed prosthetic hand - visual capture of touch, and that the prosthetic hand is the participant's own hand - illusion of ownership. Thus, for participants who experience the traditional rubber hand illusion, tactile sensation on the participant's hidden hand is referred to the prosthetic hand. In our no-touch rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner but the participant's hand - hidden from view - is not touched by the Examiner. Questionnaire ratings indicated that only individuals with vision-touch synaesthesia experienced the no-touch rubber hand illusion. Thus, synaesthetic tactile sensation on the (untouched) hidden hand was referred to the prosthetic hand. These individuals also demonstrated proprioceptive drift (a change, from baseline, in proprioceptively perceived position) of the hidden hand towards the location of the prosthetic hand, and a pattern of increased proprioceptive drift with increased trial duration (60 sec, 180 sec, 300 sec). The no-touch rubber hand paradigm was an excellent method to authenticate vision-touch synaesthesia because participants were naïve about the rubber hand illusion, and they could not have known how they were expected to perform on either the traditional or the no-touch rubber hand paradigm.