Spatiotemporal influences on the recognition of two-dimensional vibrotactile patterns on the abdomen.

Spatial and temporal factors are known to highly influence tactile perception, but their role has been largely unexplored in the case of two-dimensional (2D) pattern recognition. We investigated whether recognition is facilitated by the spatial and/or temporal separation of pattern elements, or by conditions known to favor perceptual integration, such as the ones eliciting apparent movement. 2D vibrotactile patterns were presented to the abdomen of novice participants. In Experiment 1, we manipulated the spatial (inter-tactor distance) and temporal (burst duration and inter-burst interval) parameters applied to the tracing mode (sequential activation of pattern elements). In Experiment 2, we compared display modes differing in their level of temporal overlap in the presentation of pattern elements: the static mode (simultaneous activation of pattern elements), the slit-scan mode (pattern revealed line by line), and the tracing mode. The results of both experiments reveal that (a) recognition performance increases with the isolation of pattern elements in space and/or in time, (b) spatial and temporal factors interact in pattern recognition, and (c) conditions leading to apparent movement tend to be associated with lower recognition accuracy. These results further our understanding of tactile perception and provide guidance for the design of future vibrotactile communication systems. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Affordance Realization in Climbing: Learning and Transfer.

The aim of this study was to investigate how the affordances of an indoor climbing wall changed for intermediate climbers following a period of practice during which hold orientation was manipulated within a learning and transfer protocol. The learning protocol consisted of four sessions, in which eight climbers randomly ascended three different routes of fixed absolute difficulty (5c on the French scale), as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i) a horizontal-edge route (H) was designed to afford horizontal hold grasping, (ii) a vertical-edge route (V) afforded vertical hold grasping, and (iii), a double-edge route (D) was designed to afford both horizontal and vertical hold grasping. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the hip, feet and forearms to analyze the vertical acceleration and direction (3D unitary vector) of each limb and hip in ambient space during the entire ascent. Segmentation and classification processes supported detection of movement and stationary phases for each IMU. Depending on whether limbs and/or hip were moving, a decision tree distinguished four states of behavior: stationary (absence of limb and hip motion), hold exploration (absence of hip motion but at least one limb in motion), hip movement (hip in motion but absence of limb motion) and global motion (hip in motion and at least one limb in motion). Results showed that with practice, the learners decreased the relative duration of hold exploration, suggesting that they improved affordance perception of hold grasp-ability. The number of performatory movements also decreased as performance increased during learning sessions, confirming that participants' climbing efficacy improved as a function of practice. Last, the results were more marked for the H route, while the D route led to longer relative stationary duration and a shorter relative duration of performatory states. Together, these findings emphasized the benefit of manipulating task constraints to promote safe exploration during learning, which is particularly relevant in extreme sports involving climbing tasks.

Exploratory movement generates higher-order information that is sufficient for accurate perception of scaled egocentric distance.

Body movement influences the structure of multiple forms of ambient energy, including optics and gravito-inertial force. Some researchers have argued that egocentric distance is derived from inferential integration of visual and non-visual stimulation. We suggest that accurate information about egocentric distance exists in perceptual stimulation as higher-order patterns that extend across optics and inertia. We formalize a pattern that specifies the egocentric distance of a stationary object across higher-order relations between optics and inertia. This higher-order parameter is created by self-generated movement of the perceiver in inertial space relative to the illuminated environment. For this reason, we placed minimal restrictions on the exploratory movements of our participants. We asked whether humans can detect and use the information available in this higher-order pattern. Participants judged whether a virtual object was within reach. We manipulated relations between body movement and the ambient structure of optics and inertia. Judgments were precise and accurate when the higher-order optical-inertial parameter was available. When only optic flow was available, judgments were poor. Our results reveal that participants perceived egocentric distance from the higher-order, optical-inertial consequences of their own exploratory activity. Analysis of participants' movement trajectories revealed that self-selected movements were complex, and tended to optimize availability of the optical-inertial pattern that specifies egocentric distance. We argue that accurate information about egocentric distance exists in higher-order patterns of ambient energy, that self-generated movement can generate these higher-order patterns, and that these patterns can be detected and used to support perception of egocentric distance that is precise and accurate.