David Travieso

Performance in haptic geometrical matching tasks depends on movement and position of the arms.

Previous research on the properties of haptic space has shown systematic deviations from Euclidean parallelity in haptic parallelity tasks. The mainstream explanation for these deviations is that, in order to perform the task, participants generate a spatial representation with a frame of reference that integrates egocentric and allocentric components. Several studies have shown that the amount and type of deviations are affected by the configurations with regard to the arms and the rods to be matched. The present study reports 4 experiments that further address the effects of task configurations and body movements. Experiments 1 and 2 replicate and extend previous results concerning haptic matching task and acoustic pointing tasks. The third experiment includes acoustic cues aligned differentially to the reference and test bars. The fourth experiment concerns a geometrical matching task performed in the rear peripersonal space. Results show that haptic deviations from the Euclidean space are modulated by the available cues and by the body configurations. This indicates the need for further analysis on the role of body, arm and shoulder positions, and movement effects in haptic space perception.

Tactile-Sight: A Sensory Substitution Device Based on Distance-Related Vibrotactile Flow

Sensory substitution is a research field of increasing interest with regard to technical, applied and theoretical issues. Among the latter, it is of central interest to understand the form in which humans perceive the environment. Ecological psychology, among other approaches, proposes that we can detect higher-order informational variables (in the sense that they are defined over substantial spatial and temporal intervals) that specify our interaction with the environment. When using a vibrotactile sensory substitution device, it is reasonable to ask if stimulation on the skin may be exploitable to detect higher-order variables. Motivated by this question, a portable vibrotactile sensory substitution device was built, using distance-based information as a source and driving a large number of vibrotactile actuators (72 in the reported version, 120 max). The portable device was designed to explore real environments, allowing natural unrestricted movement for the user while providing contingent real-time vibrotactile information. Two preliminary experiments were performed. In the first one, participants were asked to detect the time to contact of an approaching ball in a simulated (desktop) environment. Reasonable performance was observed in all experimental conditions, including the one with only tactile stimulation. In the second experiment, a portable version of the device was used in a real environment, where participants were asked to hit an approaching ball. Participants were able to coordinate their arm movements with vibrotactile stimulation in appropriate timing. We conclude that vibrotactile flow can be generated by distance-based activation of the actuators and that this stimulation on the skin allows users to perceive time-to-contact related environmental properties.

Predicting the lateral direction of deceptive and non-deceptive penalty kicks in football from the kinematics of the kicker

This study addresses the utility of the kinematics of penalty takers for goalkeepers in association football. Twelve professional and semi-professional players shot to one side of the goal with (deceptive condition) or without (non-deceptive condition) simulating a shot to the opposite side. The body kinematics of the penalty takers were registered with motion-capture apparatus. Correlation and regression techniques were used to determine the relation between the shot direction and aspects of the penalty takers kinematics at different moments. Several kinematic variables were strongly correlated with shot direction, especially those related to the lower part of the body. Some of these variables, including the angle of the non-kicking foot, acquired high correlations at time intervals that are useful to goalkeepers. Compound variables, here defined as linear combinations of variables, were found to be more useful than locally defined variables. Whereas some kinematic variables showed substantial differences in their relation to ball direction depending on deception, other kinematic variables were less affected by deception. Results are interpreted with the hypothesis of non-substitutability of genuine action. The study can also be interpreted as extending the correlation and regression methodology, often used to analyze variables defined at single moments, to the analysis of variables in a time continuous fashion.

Action-contingent vibrotactile flow facilitates the detection of ground level obstacles with a partly virtual sensory substitution device.

This research considers a sensory substitution device that allows the exploration of the environment through normal walking, leaning and standing. The device includes an array of 24 coin motors placed vertically on the torso, with the intensity of vibration of each motor being a function of the distance to the first-encountered object. Thresholds were determined for the detection of ground-level obstacles (raised target platforms). On average, blindfolded participants were able to detect platforms with heights of 9 to 17 cm, but the thresholds differed for different experimental conditions. Experiment 1 showed that the detection threshold is lower for use with exploratory movements than for use without exploratory movements. Experiments 2 and 3 compared dynamic groups, who made exploratory movements and received vibrotactile flow contingent on their movements, with yoked groups, who received the same vibrotactile flow as the dynamic groups independently of their own movements. The detection thresholds were lower for the dynamic groups than for the yoked groups, meaning that the contingency of vibrotactile flow on exploratory movements is important beyond a higher-order vibrotactile flow by itself.

On Potential-Based and Direct Movements in Information Spaces

Learning can be portrayed as a movement in a state space. Potential-based explanations of such movements hold that learners use a gradient-descent process to minimize a potential function. Direct explanations hold that learning is specific to information for learning. This study contrasts specific hypotheses derived from these general approaches. Participants estimated the length of arrow shafts of Müller-Lyer displays. Experiment 1 shows that learning in this paradigm can indeed be portrayed as a movement in a state space. In Experiment 2 nonveridical feedback was used in such a way that the contrasted hypotheses predicted learning in opposite directions. No learning was observed. In Experiment 3, movements in the state space were observed with practice conditions in which one of the hypotheses specified a movement in the state space whereas the other did not specify any movement. A tentative explanation for these findings is that both hypotheses are partly correct. However, more than to the empirical findings for this particular task, the authors wish to draw attention to the distinction between potential-based and direct processes—a distinction that they consider of general importance for the understanding of learning.

Wherein is Human Cognition Systematic

The “systematicity argument” has been used to argue for a classical cognitive architecture (Fodor in The Language of Thought. Harvester Press, London, 1975, Why there still has to be a language of thought? In Psychosemantics, appendix. MIT Press, Cambridge, pp 135–154, 1987; Fodor and Pylyshyn in Cognition 28:3–71, 1988; Aizawa in The systematicity arguments. Kluwer Academic Press, Dordrecht, 2003). From the premises that cognition is systematic and that the best/only explanation of systematicity is compositional structure, it concludes that cognition is to be explained in terms of symbols (in a language of thought) and formal rules. The debate, with connectionism, has mostly centered on the second premise-whether an explanation of systematicity requires compositional structure, which neural networks do not to exhibit (for example, Hadley and Hayward, in Minds and Machines, 7:1–37). In this paper, I will take issue with the first premise. Several arguments will be deployed that show that cognition is not systematic in general; that, in fact, systematicity seems to be related to language. I will argue that it is just verbal minds that are systematic, and they are so because of the structuring role of language in cognition. A dual-process theory of cognition will be defended as the best explanation of the facts.

The Ecological Level of Analysis: Can Neogibsonian Principles be Applied Beyond Perception and Action?

Is it useful to apply ecological principles, developed to understand perception and action, in research areas such as social psychology? Charles (Integrative Psychological & Behavioral Sciences 43(1) 53–66 2009) warns ecological psychologists interested in this question that much time and effort can be saved through a backwards extension to or rediscovery of the New Realism tradition. In response, we analyze what ecological psychology risks to lose with such a backwards extension and describe existing extensions of the approach not considered by Charles. According to Charles, New Realism holds that: (1) we experience reality, (2) relations are real, and (3) things are what you see when you see those things. Our arguments originate from a comparison of these principles with six recently described ecological ones: (1) organism-environment systems are the proper units of analysis, (2) environmental realities should be defined at the ecological scale, (3) behavior is emergent and self-organized, (4) perception and action are continuous and cyclic, (5) information is specificational, and (6) perception is of affordances (Richardson et al. 2008).

Stepping on Obstacles with a Sensory Substitution Device on the Lower Leg: Practice without Vision Is More Beneficial than Practice with Vision

Practice is essential for an adapted use of sensory substitution devices. Understanding the learning process is therefore a fundamental issue in this field of research. This study presents a novel sensory substitution device worn on the lower leg and uses the device to study learning. The device includes 32 vibrotactile actuators that each vibrate as a function of the distance to the nearest surface in a particular direction. Participants wearing the device were asked to approach an object and to step on the object. Two 144-trial practice conditions were compared in a pretest-practice-posttest design. Participants in the first condition practiced with vibrotactile stimulation while blindfolded. Participants in the second condition practiced with vibrotactile stimulation along with normal vision. Performance was relatively successful, both types of practice led to improvements in performance, and practice without vision led to a larger reduction in the number of errors than practice with vision. These results indicate that distance-based sensory substitution is promising in addition to the more traditional light-intensity-based sensory substitution and that providing appropriate sensorimotor couplings is more important than applying the stimulation to highly sensitive body parts. The observed advantage of practice without vision over practice with vision is interpreted in terms of the guidance hypothesis of feedback and learning.

El tiempo del reloj y el tiempo de la acción. Introducción al número monográfico sobre Tiempo y Explicación Psicológica

Resumen Este artículo examina los fundamentos de la percepción de la simultaneidad y la sucesión, del movimiento y del cambio, considerándolos como las bases sobre las que se construye la noción de tiempo. El tiempo no se percibe de forma directa, sino que su presencia es consecuencia de la constitución mutua de las nociones de permanencia y cambio. Sin la función simbólica resulta imposible concebir las nociones de pasado, presente y futuro, y el tiempo de la larga duración y de la historia. Es la acción, mediada instrumental y semióticamente, la que crea las unidades de medida que permiten conectar el tiempo vivido con el tiempo medido.

Body-scaled affordances in sensory substitution

The research field on sensory substitution devices has strong implications for theoretical work on perceptual consciousness. One of these implications concerns the extent to which the devices allow distal attribution. The present study applies a classic empirical approach on the perception of affordances to the field of sensory substitution. The reported experiment considers the perception of the stair-climbing affordance. Participants judged the climbability of steps apprehended through a vibrotactile sensory substitution device. If measured with standard metric units, climbability judgments of tall and short participants differed, but if measured in units of leg length, judgments did not differ. These results are similar to paradigmatic results in regular visual perception. We conclude that our sensory substitution device allows the perception of affordances. More generally, we argue that the theory of affordances may enrich theoretical debates concerning sensory substitution to a larger extent than has hitherto been the case.