Overview of Perception Concepts

Perception Overview

• Perception is the result of sensory stimulation.
• Basic concepts of perception can change with added information and involve processes like reasoning and problem-solving.
• Perception occurs in conjunction with bodily actions.
• True human perception is unique.
• Attempts to create artificial perception (machines) have limited success, facing unsolved problems.

Example of Perception

• Initially, a person might perceive a large piece of driftwood from afar.
• Upon closer inspection, the person realizes it is an umbrella instead.
• Exploring a coiled rope, the person makes an assumption about its continuation despite not seeing the whole object.

What is Perception?

• Experience resulting from sensory stimulation.
• Basic perception concepts adjust based on new information; they employ reasoning and problem-solving methods.
• Perceptual processes occur concurrently with actions.

Perception Difficulties for Computers

• Humans easily perceive the features of buildings and trees in a complex scene.
• Computer vision systems struggle with such complexities.
• Computer vision programs sometimes make mistakes, confusing objects with similar features. (e.g., lens cover and teapot might be categorized as a tennis ball).
• Computers have difficulty recognizing faces at oblique angles.

Why Can't Machines Perceive Like Humans?

• Inverse Projection Problem: Determining the object that created a retinal image (starting with the image and determining the object).
• Hidden or Blurred Objects: People perceive obscured or blurry objects as complete, utilizing their knowledge of the environment.
• Viewpoint Invariance: Humans seamlessly perceive objects as the same from various angles, unlike computers struggling with object recognition.

Information Used in Human Perception

• Environmental energy stimulates receptors.
• Knowledge and expectations shape the perception from the observer's perspective.

Top-Down vs. Bottom-Up Processing

• Top-down: Perception influenced by knowledge, expectations, and previous experiences (what we already know).
• Bottom-up: Perception initiated by sensory input (incoming data from our senses).

Perceiving Objects

• Context dramatically alters perceptions.
• Perception can be misleading if the context isn't understood correctly.

Perceiving People

• Emotional context impacts facial expression interpretation.
• Participants judged neutral faces differently depending on the accompanying emotional context (e.g., fear or happiness).

Perception of Language

• Top-down processing influences understanding, drawing on past experiences.
• Speech segmentation - recognizing the beginnings and ends of words in continuous speech.
• Transitional probabilities - predicting the likelihood of sounds following each other within words.

Perception of Pain

• Pain arises when receptors in the skin are stimulated.
• This is a bottom-up process.
• Pain is also shaped by expectations, attention, and distractions (Top-down processes).

Helmholtz's Unconscious Inference

• Some perceptions arise from unconscious assumptions about the environment.
• We use prior knowledge to inform perception.
• We perceive the world based on the most probable cause of a sensory event.

Perceptual Organization

• Gestalt Principles: The whole is more than the sum of its parts.
• Rejects the idea that perception is simply a sum of sensations.
• Gestalt psychology suggests intrinsic laws that govern perceptual organization.

Gestalt Principles of Perceptual Organization (Examples)

• Figure-Ground: Distinguishing figures from their background
• Good Continuation: Interpreting overlapping lines as continuous entities following a smooth path.
• Law of Pragnanz (Simplicity): Perceiving the simplest possible structure among perceptual stimuli

Principles of Similarity

• Similar things tend to be grouped together based on color, size, shape, or orientation.

Taking Environment Regularities into Account

• Characteristics that frequently appear in the environment strongly influence how we see.
• Regularities in color, spatial orientation, light sources, and function influence the kinds of objects or scenes that humans perceive.

Physical Regularities

• We readily perceive verticals and horizontals more than other orientations.
• Light often comes from above.
• Shadows indicate depth and distance.

Semantic Regularities

• Scene schemas: Our knowledge of what kinds of objects are likely to appear in different scenes.
• For example, we expect to see diamond rings in a jewelry store but not a plate of pasta.

Scene Schema Study

• People use context (scene) information to identify objects.

Bayesian Inference

• An estimate of how probable an initial belief (prior) is combined with additional evidence (likelihood) to make a perception.

Perception and Action: What and Where

• What pathway: Determining an object's identity (ventral pathway)
• Where pathway: Determining an object's location (dorsal pathway)
• Visual agnosia, a condition.
• Damage to the temporal lobe affects the ability to interpret objects.
• The patient, despite impairment in identifying objects, can still interact with them effectively (using the where pathway).

Summary

• Perception depends on both bottom-up (sensory input) and top-down (knowledge) processing.
• Both use two separate systems: perception or what pathways, and action or where pathways.

This quiz explores the fundamental concepts of perception, including how sensory stimulation impacts our understanding. It discusses the uniqueness of human perception and the challenges faced by machines in replicating this ability. Engage with examples to deepen your understanding of perceptual processes.