How Do We See a Changing World?

This chapter begins an analysis of how we see changing visual images and scenes. It explains why moving objects do not create unduly persistent trails, or streaks, of persistent visual images that could interfere with our ability to see what is there after they pass by. It does so by showing how the circuits already described for static visual form perception automatically reset themselves in response to changing visual cues, and thereby prevent undue persistence, when they are augmented with habituative transmitter gates, or MTM traces. The MTM traces gate specific connections among the hypercomplex cells that control completion of static boundaries. These MTM-gated circuits embody gated dipoles whose rebound properties autonomically reset boundaries at appropriate times in response to changing visual inputs. A tradeoff between boundary resonance and reset is clarified by this analysis. This kind of resonance and reset cycle shares many properties with the resonance and reset cycle that controls the learning of recognition categories in Adaptive Resonance Theory. The MTM-gated circuits quantitatively explain the main properties of visual persistence that do occur, including persistence of real and illusory contours, persistence after offset of oriented adapting stimuli, and persistence due to spatial competition. Psychophysical data about afterimages and residual traces are also explained by the same mechanisms.

Temporal coherency of mechanical stimuli modulates tactile form perception

The human hand can detect both form and texture information of a contact surface. The detection of skin displacement (sustained stimulus) and changes in skin displacement (transient stimulus) are thought to be mediated in different tactile channels; however, tactile form perception may use both types of information. Here, we studied whether both the temporal frequency and the temporal coherency information of tactile stimuli encoded in sensory neurons could be used to recognize the form of contact surfaces. We used the fishbone tactile illusion (FTI), a known tactile phenomenon, as a probe for tactile form perception in humans. This illusion typically occurs with a surface geometry that has a smooth bar and coarse textures in its adjacent areas. When stroking the central bar back and forth with a fingertip, a human observer perceives a hollow surface geometry even though the bar is physically flat. We used a passive high-density pin matrix to extract only the vertical information of the contact surface, suppressing tangential displacement from surface rubbing. Participants in the psychological experiment reported indented surface geometry by tracing over the FTI textures with pin matrices of the different spatial densities (1.0 and 2.0 mm pin intervals). Human participants reported that the relative magnitude of perceived surface indentation steeply decreased when pins in the adjacent areas vibrated in synchrony. To address possible mechanisms for tactile form perception in the FTI, we developed a computational model of sensory neurons to estimate temporal patterns of action potentials from tactile receptive fields. Our computational data suggest that (1) the temporal asynchrony of sensory neuron responses is correlated with the relative magnitude of perceived surface indentation and (2) the spatiotemporal change of displacements in tactile stimuli are correlated with the asynchrony of simulated sensory neuron responses for the fishbone surface patterns. Based on these results, we propose that both the frequency and the asynchrony of temporal activity in sensory neurons could produce tactile form perception.

Temporal coherence of mechanical stimulation modulates tactile form perception

The human hand can detect both form and texture information of a contact surface. The detection of skin displacement (sustained stimulus) and changes in skin displacement (transient stimulus) are thought to be mediated in different tactile channels; however, tactile form perception may use both types of information. Here, we studied whether both the temporal frequency and the temporal coherency information of tactile stimuli encoded in sensory neurons could be used to recognize the form of contact surfaces. We used the fishbone tactile illusion (FTI), a known tactile phenomenon, as a probe for tactile form perception in humans. This illusion typically occurs with a surface geometry that has a smooth bar and coarse textures in its adjacent areas. When stroking the central bar back and forth with a fingertip, a human observer perceives a hollow surface geometry even though the bar is physically flat. We used a passive high-density pin matrix to extract only the vertical information of the contact surface, suppressing tangential displacement from surface rubbing. Participants in the psychological experiment reported indented surface geometry by tracing over the FTI textures with pin matrices of the different spatial densities (1.0 and 2.0 mm pin intervals). Human participants reported that the relative magnitude of perceived surface indentation steeply decreased when pins in the adjacent areas vibrated in synchrony. To address possible mechanisms for tactile form perception in the FTI, we developed a computational model of sensory neurons to estimate temporal patterns of action potentials from tactile receptive fields. Our computational data suggest that i) the temporal asynchrony of sensory neuron responses is correlated with the relative magnitude of perceived surface indentation and ii) the spatiotemporal change of displacements in tactile stimuli are correlated with the asynchrony of simulated sensory neuron responses for the fishbone surface patterns. Based on these results, we propose that both the frequency and the asynchrony of temporal activity in sensory neurons could produce tactile form perception.

Numerical Magnitude Processing in Deaf Adolescents and Its Contribution to Arithmetical Ability

Although most deaf individuals could use sign language or sign/spoken language mix, hearing loss would still affect their language acquisition. Compensatory plasticity holds that the lack of auditory stimulation experienced by deaf individuals, such as congenital deafness, can be met by enhancements in visual cognition. And the studies of hearing individuals have showed that visual form perception is the cognitive mechanism that could explain the association between numerical magnitude processing and arithmetic computation. Therefore, we examined numerical magnitude processing and its contribution to arithmetical ability in deaf adolescents, and explored the differences between the congenital and acquired deafness. 112 deaf adolescents (58 congenital deafness) and 58 hearing adolescents performed a series of cognitive and mathematical tests, and it was found there was no significant differences between the congenital group and the hearing group, but congenital group outperformed acquired group in numerical magnitude processing (reaction time) and arithmetic computation. It was also found there was a close association between numerical magnitude processing and arithmetic computation in all deaf adolescents, and after controlling for the demographic variables (age, gender, onset of hearing loss) and general cognitive abilities (non-verbal IQ, processing speed, reading comprehension), numerical magnitude processing could predict arithmetic computation in all deaf adolescents but not in congenital group. The role of numerical magnitude processing (symbolic and non-symbolic) in deaf adolescents' mathematical performance should be paid attention in the training of arithmetical ability.

Temporal coherence of mechanical stimulation modulates tactile form perception

The human hand can detect both the form and texture of the contact surface. The detection of skin displacement (sustained stimulus) and change in skin displacement (transient stimulus) are thought to be mediated in different tactile channels; however, tactile form perception may use both channels to reconstruct an unified tactile imagery of contact surface in the brain. Here, we studied whether the temporal frequency and temporal coherence information of tactile stimuli encoded in sensory neurons could be used to recognize the form of the contact surface. We used a known tactile phenomenon, the fishbone tactile illusion (FTI), as a probe for tactile perception in humans. It uses an archetypal surface geometry that has a smooth central bar and textures (ridges and grooves) in its adjacent areas. By stroking the central bar back and forth with a fingertip, an observer typically perceives an indented surface geometry even though the bar is physically flat. We used a passive high-density pin matrix to extract only the vertical information of the contact surface, while excluding any tangential force caused by rubbing the surface. Participants in the psychological experiment reported the indented surface geometry by tracing the FTI textures with pin matrices of different spatial densities (1.0- and 2.0- mm pin intervals). Participants reported a steep decrease in the relative magnitude of the indented surface geometry when pins in the adjacent areas vibrated synchronously. To investigate possible mechanisms for tactile perception in the FTI, we developed a computational model of sensory neurons to estimate temporal patterns of action potentials from tactile receptive fields. Our computational data suggest that i) the temporal asynchrony of sensory neuron responses correlated with the relative magnitude of indented geometric perception, and ii) the temporal change of displacements in tactile stimuli correlated with the asynchrony of simulated sensory neuron responses for the fishbone surface patterns. Based on these results, we suggest that both the temporal frequency and asynchrony of activity in sensory neurons could produce tactile form perception.

Compositional Procedures in Electronic Music and the Emergence of Time Continuum

We introduce an analytical methodology to approach the perception of time in the electronic works Thema: Omaggio a Joyce (1958), by Luciano Berio, and Gesang der Jünglinge (1955–6), by Karlheinz Stockhausen. Such works have already been widely analysed and discussed. Moreover, similarities between them have been pointed out, such as the use of the voice as their main compositional material and the search for a continuum between the voice and electronic sounds. Despite their similarities, we argue that the perception of time in those works is significantly different. For that purpose, we bring theoretical references such as time concepts related to complex dynamic systems, and the perception of time according to the Gestalt theory. We discuss segmentation and texture evolution in time of both works employing graphical representations based on perceptual audio descriptors such as the mel scale and the volume. In addition, aiming to find recurrences, repetitions and variations of the spectral material in time, we apply phase space graphs addressing the values of the descriptors employed in the analysis. The features found will lead to conclusions on the emergence of time perception in which the continuity depends on the presence of similar events, periodicities and pregnancies, while discontinuity is given by the presence of more variation, instability and saliences. We emphasise the differences of form perception in those pieces, arguing that they are the result of the manipulation of sound materials and organisation in time by the composers.