A Role for Finger Properties in Exploration and Perception of Softness

Area of Science:

• * Haptics and human tactile perception.
• * Biomechanics of sensory-motor interaction.

Background:

• * Passive touch performance correlates with finger pad properties (elasticity, hydration, size).
• * Active touch involves exploratory procedures and parameter tuning for object property evaluation.
• * Force modulation is crucial for assessing properties like softness.

Purpose of the Study:

• * To investigate how finger pad size, elasticity, and hydration affect active softness perception.
• * To understand the influence of these physical properties on force-tuning and discrimination performance.
• * To explore the role of task constraints (force limits) in active touch.

Main Methods:

• * Participants performed two softness discrimination tasks under restricted (≤2N) and unconstrained force conditions.
• * Finger pad elasticity and hydration were measured using cutometer and corneometer.
• * Finger pad size was measured using calipers.
• * Hyaluronic acid treatment was applied to alter finger pad properties in one session.

Main Results:

• * Smaller finger pads led to reduced force exertion in the restricted task.
• * More hydrated and elastic fingers resulted in less force exertion in the unconstrained task.
• * Hyaluronic acid treatment diminished force-tuning in the unconstrained task, suggesting rapid adaptation to altered cues.

Conclusions:

• * Individuals adapt their exploratory forces based on intrinsic finger properties and task demands.
• * The availability of sensory cues influences force modulation strategies.
• * Adaptation to altered finger pad properties through treatment requires significant practice.