Early visual experience and the recognition of basic facial expressions: involvement of the middle temporal and inferior frontal gyri during haptic identification by the early blind.

Face perception is critical for social communication. Given its fundamental importance in the course of evolution, the innate neural mechanisms can anticipate the computations necessary for representing faces. However, the effect of visual deprivation on the formation of neural mechanisms that underlie face perception is largely unknown.

Tactile perception of nonpainful unpleasantness in relation to perceived roughness: effects of inter-element spacing and speed of relative motion of rigid 2-D raised-dot patterns at two body loci.

Rigid surfaces consisting of spatially jittered 2-D raised-dot patterns with different inter-element spacings were moved back and forth across the skin at three different speeds (10-fold range). Within each psychophysical experiment, participants numerically estimated the perceived magnitude of either unpleasantness (nonpainful) or roughness of 2-D raised-dot surfaces applied to two stationary body sites (experiment 1: fingers; experiment 2: forearm). The psychophysical functions for the two types of perceptual judgment were highly similar at both body loci; more specifically, the perceived magnitude of unpleasantness and roughness both increased monotonically as a power function of increasing inter-element spacing, with the rate of growth declining at the upper end of the continuum.

Haptic object perception: spatial dimensionality and relation to vision.

Enabled by the remarkable dexterity of the human hand, specialized haptic exploration is a hallmark of object perception by touch. Haptic exploration normally takes place in a spatial world that is three-dimensional; nevertheless, stimuli of reduced spatial dimensionality are also used to display spatial information. This paper examines the consequences of full (three-dimensional) versus reduced (two-dimensional) spatial dimensionality for object processing by touch, particularly in comparison with vision.

Irrelevant visual faces influence haptic identification of facial expressions of emotion.

This study demonstrates that when people attempt to identify a facial expression of emotion (FEE) by haptically exploring a 3D facemask, they are affected by viewing a simultaneous, task-irrelevant visual FEE portrayed by another person. In comparison to a control condition, where visual noise was presented, the visual FEE facilitated haptic identification when congruent (visual and haptic FEEs same category). When the visual and haptic FEEs were incongruent, haptic identification was impaired, and error responses shifted toward the visually depicted emotion.

Learning and generalization in haptic classification of 2-D raised-line drawings of facial expressions of emotion by sighted and adventitiously blind observers.

Sighted blindfolded individuals can successfully classify basic facial expressions of emotion (FEEs) by manually exploring simple 2-D raised-line drawings (Lederman et al 2008, IEEE Transactions on Haptics 1 27-38). The effect of training on classification accuracy was assessed by sixty sighted blindfolded participants (experiment 1) and by three adventitiously blind participants (experiment 2). We further investigated whether the underlying learning process(es) constituted token-specific learning and/or generalization.

Representing human hands haptically or visually from first-person versus third-person perspectives.

Humans can recognise human body parts haptically as well as visually. We employed a mental-rotation task to determine whether participants could adopt a third-person perspective when judging the laterality of life-like human hands. Female participants adopted either a first-person or a third-person perspective using vision (experiment 1) or haptics (experiment 2), with hands presented at various orientations within a horizontal plane.

Brain networks involved in haptic and visual identification of facial expressions of emotion: an fMRI study.

Previous neurophysiological and neuroimaging studies have shown that a cortical network involving the inferior frontal gyrus (IFG), inferior parietal lobe (IPL) and cortical areas in and around the posterior superior temporal sulcus (pSTS) region is employed in action understanding by vision and audition. However, the brain regions that are involved in action understanding by touch are unknown. Lederman et al.

Functional specialization and convergence in the occipito-temporal cortex supporting haptic and visual identification of human faces and body parts: an fMRI study.

Humans can recognize common objects by touch extremely well whenever vision is unavailable. Despite its importance to a thorough understanding of human object recognition, the neuroscientific study of this topic has been relatively neglected. To date, the few published studies have addressed the haptic recognition of nonbiological objects.

Assessing subclinical tactual deficits in the hand function of diabetic blind persons at risk for peripheral neuropathy.

Objective: To assess subclinical impairments in tactual hand function produced by diabetes mellitus in late-blind adults with diabetic retinopathy.

Design: The survey compares diabetic blind with nondiabetic blind and blindfolded sighted controls in terms of their performance on a battery of tests that assess tactual hand function.

Setting: Subjects were evaluated at their rehabilitation program center in Madrid.

Haptic face processing.

We present an overview of a new multidisciplinary research program that focuses on haptic processing of human facial identity and facial expressions of emotion. A series of perceptual and neuroscience experiments with live faces and/or rigid three-dimensional facemasks is outlined. To date, several converging methodologies have been adopted: behavioural experimental studies with neurologically intact participants, neuropsychological behavioural research with prosopagnosic individuals, and neuroimaging studies using fMRI techniques.

Haptic roughness perception of linear gratings via bare finger or rigid probe.

The magnitude of perceived roughness was haptically estimated as subjects freely explored linear gratings with either the bare finger or a rigid stylus-shaped probe. A considerably expanded range of ridge and groove width was investigated, relative to the extant literature. The four experiments collectively indicate that, for both finger and probe-end effectors, the variance in the estimates of perceived roughness was predominantly predicted by a single parameter: groove width.

A haptic face-inversion effect.

We examined whether a face-inversion effect occurs when participants explore faces by touch. We used a haptic version of the inversion paradigm with 3-D clay facemasks and non-face control objects (teapots) moulded from real objects. Young, neurologically intact, blindfolded participants performed a temporally unconstrained haptic same/different task in each of four stimulus conditions: upright facemasks, inverted facemasks, upright teapots, and inverted teapots.

Multisensory activation of the intraparietal area when classifying grating orientation: a functional magnetic resonance imaging study.

Humans can judge grating orientation by touch. Previous studies indicate that the extrastriate cortex is involved in tactile orientation judgments, suggesting that this area is related to visual imagery. However, it has been unclear which neural mechanisms are crucial for the tactile processing of orientation, because visual imagery is not always required for tactile spatial tasks.

The influence of familiarity on brain activation during haptic exploration of 3-D facemasks.

Little is known about the neural substrates that underlie difficult haptic discrimination of 3-D within-class object stimuli. Recent work [A.R.

Haptic face identification activates ventral occipital and temporal areas: an fMRI study.

Many studies in visual face recognition have supported a special role for the right fusiform gyrus. Despite the fact that faces can also be recognized haptically, little is known about the neural correlates of haptic face recognition. In the current fMRI study, neurologically intact participants were intensively trained to identify specific facemasks (molded from live faces) and specific control objects.

Imagining material versus geometric properties of objects: an fMRI study.

Two experiments are reported that used fMRI to compare the brain activation during the imagery of material and geometric object features. In the first experiment, participants were to mentally evaluate objects along either a material dimension (roughness, hardness and temperature; e.g.

Tactile estimation of the roughness of gratings yields a graded response in the human brain: an fMRI study.

Human subjects can tactually estimate the magnitude of surface roughness. Although many psychophysical and neurophysiological experiments have elucidated the peripheral neural mechanisms that underlie tactile roughness estimation, the associated cortical mechanisms are not well understood. To identify the brain regions responsible for the tactile estimation of surface roughness, we used functional magnetic resonance imaging (fMRI).

Haptic identification of common objects: effects of constraining the manual exploration process.

In this article, we address the effects on haptic recognition of common objects when manual exploration is constrained by using two kinds of rigid links--sheaths (Experiment 1A) and probes (Experiments 1B and 2). The collective effects of five different constraints are considered, including three from previous research (i.e.

Haptic processing of the location of a known property: does knowing what you've touched tell you where it is?

The relationship between knowing where a haptic property is located and knowing what it is was investigated using a haptic-search paradigm. Across trials, from one to six stimuli were presented simultaneously to varying combinations of the middle three fingertips of both hands. Participants reported the presence/absence of a target or its location for four perceptual dimensions: rough/smooth, edge/no edge, relative position (right/left), and relative orientation (right/left).

Haptic face recognition and prosopagnosia.

Cases of cross-modal influence have been observed since the beginning of psychological science. Yet some abilities like face recognition are traditionally only investigated in the visual domain. People with normal visual face-recognition capacities identify inverted faces more poorly than upright faces.

Watching a cursor distorts haptically guided reproduction of mouse movement.

Participants moved a mouse along a force-feedback-defined linear path, either without vision or while watching a cursor set to 1 of 3 levels of visual:haptic gain (all >1:1). They attempted to haptically reproduce the movement without visual feedback. Errors increased with gain, reaching 70% overestimation at the highest gain.

Perceptual judgement, grasp point selection and object symmetry.

Object symmetry is a visual attribute that may contribute to perceptual judgement and to action. We evaluated the effects of varying the physical symmetry of planar objects (presence versus absence) on both aspects. In Experiment 1, subjects estimated the magnitude of visually perceived symmetry of the objects.

Feeling textures through a probe: effects of probe and surface geometry and exploratory factors.

Vibratory roughness perception occurs when people feel a surface with a rigid probe. Accordingly, perceived roughness should reflect probe and surface geometry, exploratory speed, and force. Experiments 1 and 2 compared magnitude estimation of roughness with the bare finger and two types of probes, one designed to eliminate force moments, under the subject's active control.

Representing spatial location and layout from sparse kinesthetic contacts.

Participants' fingers were guided to 2 locations on a table for 3 s, then back to the start. They reported distances and angles between the locations by (a) replacing 1 or 2 fingers, (b) translating the contacted configuration, or (c) estimating distance or angle alone. Distance error increased across these conditions.

Using tactile features to help functionally blind individuals denominate banknotes.

This study, which was conducted for the Bank of Canada, assessed the feasibility of presenting a raised texture feature together with a tactile denomination code on the next Canadian banknote series ($5, $10, $20, $50, and $100). Adding information accessible by hand would permit functionally blind individuals to independently denominate banknotes. In Experiment 1, 20 blindfolded, sighted university students denominated a set of 8 alternate tactile feature designs.