Alessandra Cecilia Jacomuzzi

Distance Perception in Autism and Typical Development

Children with autism and typically developing children walked blindfolded to a previously seen target (blindwalking task) and matched the frontal to the sagittal extent of a pattern formed by ropes on the ground (L-matching task). All participants were accurate in the blindwalking task. Children with autism were also very accurate in the matching task. By contrast, in the matching task typically developing children made substantial underestimations that were inversely correlated with age. These findings support models that posit independent representations for the egocentric distance to a target location and for the spatial extent to a target object relative to the other spatial extents. These latter representations involve a form of large-scale pattern perception that may mature more slowly than representations of egocentric distance and develop atypically in autism.

Perceiving occlusion through auditory–visual substitution

The development of visual prostheses for the blind has a long history. Presumably, the use of tools such as a long cane for haptic exploration beyond peripersonal space was already common in antiquity. Seeing-eye dogs may also be considered as a special kind of (animate) prosthesis. Modern prosthetic visual devices aim at conveying useful information about the environment to a blind individual. They do not try to induce the conscious, qualitative experience of seeing (a goal that may well prove impossible) or to provide the full complexity of visual information. Rather, they aim at offering sensory support to enhance a blind individual’s mobility in nonfamiliar environments. We find that modern prostheses divide into two broad categories: invasive (artificial retinas or direct cortical stimulation systems), and noninvasive (sensory substitution systems). According to preliminary observations, blind individuals can learn to use invasive prostheses to perform visual tasks surprisingly fast. However, this type of prosthetic device also has obvious disadvantages. It requires expensive neurosurgery and hardware, and there are strong suspects that it may not work at all with early blind patients. Non-invasive prostheses, conversely, do not require surgery. In addition, there are reasons to think that the sensory substitution approach may work with early blind patients. Prosthetic systems based on sensory substitution have been studied for almost 40 years. They are based on the idea of substituting visual stimulation with stimulation from another, intact sensory system such as the tactile system (Bach-y-Rita 1968) or the auditory system (Cronlly-Dillon and Persaud 2000;

Vision-for-perception and vision-for-action in typical development, autism, and Parkinson's disease

According to the two-visual-system hypothesis (Milner and Goodale 1995), after V1 the visual system splits into vision-for-action and vision-for-perception modules. Specifically, the dorsal subsystem is proposed to specialize in the visual guidance of actions, whereas the ventral subsystem in object perception and recognition. Support for the two-visual-systems hypothesis has come from monkey and human studies using a variety of techniques, including neuroimaging, neuropsychological, neurophysical, psychophysical, and behavioral methods (for a recent review, see Goodale and Westwood 2004). In particular, four commonly accepted criteria for the modularity of cognitive systems are broadly tested in the literature: association with fixed neural architecture, obligatory output, information encapsulation, and specific breakdown patterns after damage (Fodor 1983). Very few studies have tested other criteria for modularity, such as, for instance, the idea that independent modules may exhibit characteristic pace and sequencing in their ontogenetic development. Rival et al. (2004), among others, studied motor and perceptual responses to illusions in children. They reported that visuomanual pointing responses were unaffected by illusions, whereas visual matches were. However, current opinions diverge on the interpretation of dissociations between perceptual and motor tasks in visual illusions (Bruno 2001; Carey 2001; Franz 2001; Milner and Dyde 2003) and therefore these findings are not conclusive.

Ames’s window in proprioception

When holding a small-scale model of Amess trapezoidal window with the arms fully extended, several observers experience a striking proprioceptive distortion (eg one hand appears farther from the other, or one arm appears longer than the other). However, data from a matching experiment suggest that the proprioceptive misalignment of the hands is, in fact, rather less than the apparent slant of the window when this is not held. This finding argues against a ‘visual-capture’ account, supports an explanation in terms of bimodal integrative processes, and underscores the importance of supplementing phenomenological observations with objective measures.

Percezioni, ragionamenti e illusioni

Il senso comune tende a credere all’esistenza delle illusioni ottiche e percettive ma difficilmente sostiene la tesi di un ragionamento illusorio. Nel campo della psicologia del ragionamento si parla piuttosto di errori di ragionamento, che l’esperienza puo correggere e modificare. Per questo nel tempo si e consolidata la credenza che esista una netta distinzione tra le une e le altre. Le prime sarebbero piu forti, le seconde piu deboli e con possibilita di correzione. In questo lavoro intendo dimostrare, attraverso la presentazione e analisi di una topologia delle illusioni, che esiste, in realta, una struttura universale sottostante a ogni tipo di illusione. Questa stessa struttura e quella che ci permette di parlare di un criterio universale per identificare le illusioni, una parte fondamentale del mondo esterno.

Cubo o sfera? Nuove prospettive per il Quesito di Molyneux

Ci sono domande che rimangono tali per secoli e anche se non trovano risposta riescono a mantenere vivo il nostro interesse, diventando col tempo dei veri e propri rompicapi. Una di queste e quella formulata da William Molyneux nel 1688, conosciuta come il Quesito di Molyneux. In questo caso l’interesse non riguarda solo la domanda in se ma anche la sua infinita storia. 1. La storia del Quesito di Molyneux Il Quesito di cui parleremo in queste pagine fa la sua comparsa, per la prima volta, in...