Perception and Behavioural Aspects: How Perceptual Processes Influence Skilled Performance

Perception and Behavioural Aspects

Introduction

This unit explores how perceptual processes influence the performance of skills, focusing on reaction time, pattern recognition, visual acuity, optical flow, and time-to-contact. Understanding these concepts is essential for explaining differences between skilled and unskilled performers in various activities, especially sports.

Discrimination Reaction Time (DRT)

Types of Reaction Time

• Simple Reaction Time: The time taken to respond to a single stimulus with a single response.

• Choice Reaction Time: The time taken when different responses are required for different stimuli.

• Discrimination Reaction Time (DRT): The time taken when multiple stimuli are present, but only one requires a response; the others are ignored.

DRT is concerned with maintaining accuracy while responding quickly, often in forced-paced tasks. For example, in volleyball, an attacker must decide to spike or tip based on defenders' actions.

• Factors Impacting DRT:

  • Similarity of stimuli: The more alike two sets of stimuli, the longer it takes to respond.

  • Magnitude of difference: Greater differences between stimuli (e.g., height of bars) make discrimination easier and faster.

Example: In volleyball, if both defenders jump, the attacker tips; if neither jumps, the attacker spikes; if one jumps higher, the attacker spikes over the lower defender.

Crossman's Confusion Function

Similarity of Stimuli and Decision Making

Crossman's Confusion Function describes the relationship between the discriminability of stimuli and reaction time. The larger the difference (Y) between stimuli, the easier and faster the decision.

• Formula:

$\text{DRT} = a + b \left( \frac{1}{\log X_1 - \log X_2} \right) \text{ bits}$

• X1: Larger stimulus

• X2: Smaller stimulus

• Bit: Amount of information required to reduce uncertainty by half

Tasks with small differences between stimuli (small Y) are more difficult and require longer DRT.

Pattern Recognition

Role in Skilled Performance

Recognition of complex patterns is crucial for differentiating skilled and unskilled performers, especially in sports. Fundamental perceptual abilities alone cannot explain skill differences; the ability to recognize meaningful patterns is critical for success.

• Expert vs. Novice:

  • Experts notice features and patterns that novices do not.

  • Experts have organized, context-rich knowledge stored in long-term memory (LTM).

  • Experts retrieve relevant information with little effort.

Chunking: Experts use chunking to group information into meaningful units (e.g., 'FBI' instead of 'F B I').

Example: In chess, experts recognize normal positions and patterns more efficiently than novices, but both struggle with random positions.

Visual Acuity

Static and Dynamic Visual Acuity

• Static Visual Acuity: Ability to distinguish details of stationary objects when both the object and observer are still.

• Dynamic Visual Acuity: Ability to identify details of moving objects or when there is relative movement between observer and object.

Normal visual acuity is not a limiting factor for performance, but below-average vision may hinder skill execution.

Optical Flow Field

Perception of Motion and Position

An optical flow field refers to the expansion, contraction, or regular movement of all visual stimuli (points, lines, edges) in the field of view. It provides cues for position and motion, aiding in navigation and movement control.

• Novice drivers may not use optical flow efficiently, leading to less effective movement decisions compared to experienced drivers.

Example: The expansion pattern of lines in a hallway illustrates optical flow, helping to perceive movement and distance.

Time to Contact (Tau)

Timing Information for Moving Objects

Time to contact (tau) is crucial for activities requiring precise timing, such as driving or catching a ball. It provides cues for initiating movement and avoiding collisions.

• Formula:

$\text{tau (time to contact)} = \frac{\text{size of image (on retina)}}{\text{velocity of expansion of image (on retina)}}$

• The faster an object fills the visual field, the sooner contact will occur.

• Variables: Z = distance to eye, S = object size, V = velocity, θ = angular size.

Example: A baseball outfielder uses tau to determine where and when to catch a fly ball, based on the ratio of tau Y (vertical position) to tau X (horizontal position):

• If $\frac{\text{Tau Y}}{\text{Tau X}} = 1$, the ball intersects the eye.

• If $< 1$, the ball lands in front of the fielder.

• If $> 1$, the ball lands behind the fielder.

Summary

• Skilled performers recognize relevant perceptual patterns quickly due to automated processing and storage in long-term memory.

• Systematic training in perceptual features can accelerate learning for beginners.

• Perceptions of patterns rely on vision, including information about size, movement, and distance of objects in the environment.

Table: Comparison of Novice and Expert Pattern Recognition

Feature	Novice	Expert
Pattern Recognition	Limited, focuses on isolated details	Recognizes meaningful patterns and features
Knowledge Organization	Fragmented, less context	Contextualized, organized for flexible retrieval
Information Processing	Slower, more effortful	Automated, less attentional effort

Additional info: These notes expand on the lecture slides by providing definitions, formulas, and examples for each concept, ensuring a self-contained study guide for psychology students.