The accuracy of ‘haptically’ measured geographical slant perception

In two recent issues of Acta, the widely accepted view of Proffitt (2006), that ‘haptic’ measures of perceived geographical slant are generally accurate, and dissociated from explicit overestimates, came under intense scrutiny (Durgin, Hajnal, Li, Tonge, and Stigliani, 2010; 2011). Durgin and colleagues' challenge to this account centred on the claim that Proffitt's haptic’ measure of geographical slant, the palm-board, may be accidently accurate due to restricted movements available at the wrist. Two experiments reported here compare the accuracy of Proffitt's palm-board with an alternative measure of geographical slant perception, the Palm-Controlled Inclinometer (PCI), which allows participants to use wrist, elbow and shoulder movements to match slant with their hand. Participants (N = 320) made slant judgements using both measures, across five hills and five staircases with 32 participants for each stimulus angle (4.5°–31°). Results for the palm-board replicated those of Proffitt and co-workers, overestimation at shallow angles (≤ 14°), contrasted with underestimation at steeper angles (≥ 23°), whereas estimates made using the PCI had a greater degree of accuracy for steeper slopes. A follow-up experiment tested the accuracy of the palm-board and PCI for surfaces in near space to repeat the design of Durgin et al. (2010, experiment 1). Participants (N = 20) used the palm-board and PCI to judge the angle of slanted blocks (25°, 30°). As with traversable slopes, PCI judgements did not differ from the actual angle of the blocks whereas the palm-board measure underestimated. ‘Haptic’ measures of geographical slant perception can be accurate for relatively steep slopes, in both near and far space.     

The role of object motion in forging long-term representations of objects

It has been suggested that objects are represented as collections of two dimensional images. Although possible in theory, such a representation must first be built, which presupposes a mechanism for collating these images. This is not trivial. Any such mechanism would have to be able to group images which differ considerably in appearance. One possible solution to this problem is to associate those images whose appearance is closely temporally correlated, on the assumption that multiple views of an object are frequently experienced in close temporal succession. This paper describes evidence for the influence of just such a mechanism in human observers, and its effect on long-term representations of initially novel faces. Discrimination performance for previously viewed faces is shown to depend on whether views of the two faces being discriminated, had previously been seen in close temporal succession or not. Irrespective of the preferred theory of how humans represent objects, these results reveal strong evidence for a novel, time-based learning mechanism that strongly influences within-category discrimination.     

The Role of Attachment and Maladaptive Emotion Regulation Strategies in the Development of Bulimic Symptoms in Adolescents

Following the theoretical propositions of the Emotion Regulation model of attachment, the current study investigated whether attachment anxiety and attachment avoidance might play a differential contributing role in the development of bulimic symptoms, through assumed differences in adopting specific maladaptive emotion regulation strategies in a sample of adolescents. Developmentally appropriate self-report questionnaires were administered to a community sample of 397 adolescents (Mean age: 14.02; 62.7% female) and this at 2 time points with a 1-year time lag. Results provided longitudinal evidence for the Emotion Regulation model of attachment in confirming the differential contributing role of the attachment dimensions on the development of bulimic symptoms in a sample of adolescents. More specifically, attachment anxiety seemed to be related to bulimic symptoms through rumination, while attachment avoidance through emotional control. These results may have clinical implications for assessment and treatment of bulimic symptoms in adolescents.     

<Emphasis Type="Italic">Doctor Anonymous</Emphasis>: Creating Contexts for Homosexuality as Mental Illness

In this essay, the author describes how he faced institutionalized homophobia during his psychiatric training, and how he later wrote a play inspired by the life of a gay psychiatrist. Despite Freud’s supportive stance, homosexuality aroused the antipathy of American organized psychiatry and psychoanalysis and came to be listed as an illness in the Diagnostic and Statistical Manual (DSM). Dr. John E. Fryer outed himself as “Dr. H Anonymous” at a 1972 meeting of the American Psychiatric Association, and the next year homosexuality was removed from the DSM. The 2014 play Doctor Anonymous offers a fictionalized account of this watershed moment in the history of the gay rights movement. The author discusses his own psychotherapeutic work with gay male patients, including those who had previously been treated with conversion therapy, and explores how the play mirrors his own life experience and the experience of his patients.     

Concurrent Cortical Representations of Function- and Size-Related Object Affordances: An fMRI Study

Previous work has shown that the perception of a graspable object may automatically potentiate actions that are tailored to specific action-related features of the object (e.g., its size) and may be related to its immediate grasping as well as to its long-term, functional use. We investigated the neural correlates of function- and size-related object affordances that may be concurrently potentiated by a graspable object. Participants were lying in a MR scanner holding a large switch in one hand and a small switch in the other hand. They passively attended a large or a small object with clearly separated functional and graspable end that was displayed centrally at an average angle of 45 degrees. Participants responded to the direction of an arrow that was overlaid on the object after a mean period of 1,000 ms after object onset and was pointing to the left or to the right with equal probability. Response times were shorter when the arrow pointed to the functional end of the object and when the responses were made with the switch that was congruent to the size of the perceived object. A clear distinction was found in the representation of function- and size-related affordances; the former was represented in the posterior parietal cortex and the latter in prefrontal, premotor, and primary sensorimotor cortices. We conclude that different aspects of object-directed actions may be automatically potentiated by individual object features and are represented in distinct brain areas.     

Motor excitability is reduced prior to voluntary movements in children and adolescents with Tourette syndrome

Tourette syndrome (TS) is a neuro‐developmental disorder characterized by the occurrence of motor and vocal tics: involuntary, repetitive, stereotyped behaviours that occur with a limited duration, often typically many times in a single day. Previous studies suggest that children and adolescents with TS may undergo compensatory, neuroplastic changes in brain structure and function that help them gain control over their tics. In the current study we used single‐pulse and dual‐site paired‐pulse transcranial magnetic stimulation (TMS), in conjunction with a manual choice reaction time task that induces high levels of inter‐manual conflict, to investigate this conjecture in a group of children and adolescents with TS, but without co‐morbid Attention Deficit Hyperactivity Disorder (ADHD). We found that performance on the behavioural response‐conflict task did not differ between the adolescents with TS and a group of age‐matched typically developing individuals. By contrast, our study demonstrated that cortical excitability, as measured by TMS‐induced motor‐evoked potentials (MEPs), was significantly reduced in the TS group in the period immediately preceding a finger movement. This effect is interpreted as consistent with previous suggestions that the cortical hyper‐excitability that may give rise to tics in TS is actively suppressed by cognitive control mechanisms. Finally, we found no reliable evidence for altered patterns of functional inter‐hemispheric connectivity in TS. These results provide evidence for compensatory brain reorganization that may underlie the increased self‐regulation mechanisms that have been hypothesized to bring about the control of tics during adolescence.