Anorexia nervosa and oversized experiences

Perceiving affordances and the problem of visually indiscernible kinds

In this study, I defend the claim that we can perceptually experience what objects afford when we engage with objects belonging to natural or artificial categorical high-level kinds. Experiencing affordances perceptually positions us to act in specific ways. The main aim of this study was to argue that this view has explanatory advantages over alternative views. An increasingly popular view within the philosophy of perception, most famously defended by Susanna Siegel, claims that we sometimes visually experience natural and artificial objects as belonging to categorical high-level kinds. When visually experiencing a lemon, one does not only experience its low-level properties such as shape and color, sometimes one also experiences the object as a lemon. A challenge arises when attempting to explain what happens when one experiences an object that is experientially indistinguishable from another object, yet these objects belong to different high-level categorical kinds. For instance, if someone perceptually experiences a lemon as a lemon, her experience can be considered as accurately representing or presenting a lemon. However, if the subject perceptually experiences a lemon-shaped soap bar, which cannot be discriminated from a real lemon by sight alone, the experience is deemed inaccurate because there is no real lemon present. The problem is that such a judgment seems counterintuitive; unlike with hallucinations and illusions, there seems to be nothing wrong with how the object appears. Therefore, it is difficult to understand how the mistake could be a perceptual mistake. I will first present arguments supporting the claim that when we visually encounter objects such as lemons, we sometimes also perceive the affordances of these objects-what they provide or offer us. I will further argue that this perspective on affordances offers a more compelling explanation than other alternative accounts when it comes to our perception of visually indistinguishable objects that nonetheless belong to categorically distinct high-level kinds.

Hypnotic suggestion versus sensory modulation of bodily awareness

Bodily awareness arises from somatosensory, vestibular, and visual inputs but cannot be reduced to these incoming sensory signals. Cognitive factors are known to also impact bodily awareness, though their specific influence is poorly understood. Here we systematically compared the effects of sensory (bottom-up) and cognitive (top-down) manipulations on the estimated size of body parts. Toward this end, in a repeated-measures design, we sought to induce the illusion that the right index finger was elongating by vibrating the biceps tendon of the left arm whilst participants grasped the tip of their right index finger (Lackner illusion; bottom-up) and separately by hypnotic suggestion (top-down), with a sham version of the Lackner illusion as an active control condition. The effects of these manipulations were assessed with perceptual and motor tasks to capture different components of the representation of body size. We found that hypnotic suggestion significantly induced the illusion in both tasks relative to the sham condition. The magnitudes of these effects were stronger than those in the Lackner illusion condition, which only produced a significantly stronger illusion than the sham condition in the perceptual task. We further observed that illusion magnitude significantly correlated across tasks and conditions, suggesting partly shared mechanisms. These results are in line with theories of separate but interacting representational processes for perception and action and highlight the influence of cognitive factors on low-level body representations.

Belief Inflexibility and Cognitive Biases in Anorexia Nervosa-The Role of the Bias against Disconfirmatory Evidence and Its Clinical and Neuropsychological Correlates

The aim of this study was to explore, in a sample of patients with a diagnosis of AN, the ability to question their first impression and, in particular, the willingness to integrate their prior ideas and thoughts with additional progressive incoming information. A total of 45 healthy women and 103 patients with a diagnosis of AN, consecutively admitted to the Eating Disorder Padova Hospital-University Unit, underwent a broad clinical and neuropsychological assessment. All participants were administered the Bias Against Disconfirmatory Evidence (BADE) task, which specifically investigates belief integration cognitive bias. Acute AN patients showed a significantly greater bias toward disconfirming their previous judgment, in comparison to healthy women (BADE score, respectively, 2.5 ± 2.0 vs. 3.3 ± 1.6; Mann-Whitney test, p = 0.012). A binge-eating/purging subtype of AN individuals, compared to restrictive AN patients and controls, showed greater disconfirmatory bias and also a significant propensity to uncritically accept implausible interpretations (BADE score, respectively, 1.55 ± 1.6 and 2.70 ± 1.97 vs. 3.33 ± 1.63; Kruskal-Wallis test, p = 0.002 and liberal acceptance score, respectively, 1.32 ± 0.93 and 0.92 ± 1.21 vs. 0.98 ± 0.75; Kruskal-Wallis test p = 0.03). Abstract thinking skills and cognitive flexibility, as well as high central coherence, are neuropsychological aspects positively correlated with cognitive bias, in both patients and controls. Research into belief integration bias in AN population could enable us to shed light on hidden dimensional aspects, facilitating a better understanding of the psychopathology of a disorder that is so complex and difficult to treat.

Exploring the Experiences of Women Who Develop Restrictive Eating Behaviours After Bariatric Surgery

OBJECTIVE

This study aimed to explore the experiences of women who had developed excessively restrictive eating behaviours following bariatric surgery.

METHOD

Five female participants, who were at least nine months post-bariatric surgery and exhibiting restrictive eating behaviours, were recruited from Bariatric Surgery Psychology Services and asked to complete qualitative face-to-face semi-structured interviews. The data was analysed using interpretative phenomenological analysis (IPA).

RESULTS

Three super-ordinate themes emerged: (1) experiences of weight stigma and weight history on self, (2) the impact of loose skin, (3) thoughts about food and disordered eating patterns. These captured the impact of past weight-related experiences-including weight stigma, intense fears of weight gain, negative cognitions about the self, the impact of excess skin, changes in the way the women thought about food and restrictive eating behaviours.

DISCUSSION

This study is one of the first to specifically explore restrictive eating disorders after bariatric surgery using a qualitative approach. The findings of this study may offer helpful aspects for professionals to hold in mind when identifying individuals with problematic restrictive eating behaviours following bariatric surgery. Body contouring surgery, internalised weight bias and weight stigma are explored in relation to the post-bariatric surgery treatment pathway. The current diagnostic criterion for anorexia nervosa are discussed to highlight difficulties in diagnosing this presentation in the post-bariatric surgery population, where people can have BMIs over 25 kg/m2 but are severely restricting energy intake.

How are the spatial characteristics of the body represented? A reply to Pitron & de Vignemont

In their article, Pitron and de Vignemont (2017) provide an insightful and well overdue discussion of the relationship between long-term body representation models and Alice in Wonderland syndrome. Here, I supplement their discussion with a number of observations. First, I present a cautionary note regarding the interpretation of experiential changes in body size as reflective of changes in the content of body representations. Second, I show how their evidence contradicts an alternative model of body representation arising from research into anorexia nervosa-the "LTB" hypothesis. Finally, I highlight a significant issue with their proposed co-construction model.

Explaining body size beliefs in anorexia

INTRODUCTION

Cognitive neuropsychiatry has had much success in providing theoretical models for the causal origins of many delusional beliefs. Recently, it has been suggested that some anorexia nervosa patients' beliefs about their own body size should be considered delusions. As such, it seems high time the methods of cognitive neuropsychiatry were turned to modelling the false body size beliefs of anorexics.

METHODS

In this paper, I adopt an empiricist approach to modelling the causal origins of false body size beliefs in anorexia. Within the background of cognitive neuropsychiatry, empiricist models claim that abnormal beliefs are grounded by abnormal experiences bearing similar content.

RESULTS

I discuss the kinds of abnormal experiences of body size anorexics suffer from which could ground their false beliefs about body size. These oversized experiences come in three varieties: false self-other body comparisons, spontaneous mental imagery of a fat body and distorted perception of affordances.

CONCLUSIONS

Further theoretical and empirical research into the oversized experiences which anorexics suffer from presents a promising avenue for understanding and treating the disorder.

Taxonomising delusions: content or aetiology?

INTRODUCTION

Many theoretical treatments assume (often implicitly) that delusions ought to be taxonomised by the content of aberrant beliefs. A theoretically sound, and comparatively under-explored, alternative would split and combine delusions according to their underlying cognitive aetiology.

METHODS

We give a theoretical review of several cases, focusing on monothematic delusions of misidentification and on somatoparaphrenia.

RESULTS

We show that a purely content-based taxonomy is empirically problematic. It does not allow for projectability of discoveries across all members of delusions so delineated, and lumps together delusions that ought to be separated. We demonstrate that an aetiological approach is defensible, and further that insofar as content-based approaches are plausible, it is only to the extent that they implicitly link content to aetiology.

CONCLUSIONS

We recommend a more explicit focus on cognitive aetiology as the grounds for delusion taxonomy, even when that would undermine traditional content-based boundaries. We also highlight the iterative and complex nature of evidence about aetiologically grounded taxonomies.