Introduction to Perception: Key Concepts and Historical Context

Perception is a biological and philosophical topic, with principles evident in media (e.g., The Lord of the Rings) and historical research.
The course covers biological sensation, then high-level perceptual principles across multiple senses.
Forced perspective illustrates perceptual tricks.

Filmmakers use forced perspective to manipulate apparent size, making characters like Frodo appear much smaller than Gandalf.
Mechanism: A fixed camera positions objects at different distances (Frodo farther than Gandalf) but aligns them to appear equidistant to the viewer. This exploits how the brain interprets image size as actual size without fully compensating for distance.
This technique leverages perceptual principles for convincing visual effects, often over less realistic CGI.

The course examines each sensory system from physiology to advanced perceptual principles.
Historical figures such as Rene Descartes (perception mechanisms) and Wilhelm Wundt (founder of experimental psychology, elementary sensations) are discussed.
Wundt’s idea: elementary sensations combine to form perception, but introspection couldn't fully map all stages.
A fundamental gap exists between sensation (detection) and perception (interpretation), a recurring course theme.

Problem: Perception involves processing stages beyond elementary sensations, creating a gap between receptor activity and conscious percepts.
Sensation: Biological conversion of physical energy into neural signals at receptor cells (e.g., light to photoreceptors, sound to hair cells).
Perception: The brain's construction of a coherent, meaningful interpretation from these neural signals.
Aim: Understand how the brain bridges this sensation-perception gap.

This framework analyzes perception in steps:
- Distal object: The object/event in the world.
- Physical medium: How the distal object’s energy travels to the senses.
- Proximal stimulus: The physical energy directly stimulating sensory receptors.
- Perceptual object: The brain's interpretation of the distal object, which corresponds but isn't always a perfect match due to influence from knowledge and expectations.

Example: Gandalf and Balrog scene.
Distal object: The scene itself.
Sensory modalities: Vision (light energy) and Hearing (sound waves).
Proximal stimulation: Retina receptors (rods/cones) for vision; cochlea hair cells for hearing.
Perceptual object: A coherent, integrated multisensory perception of the scene.

Rods and cones in the retina are primary transducers, converting light energy into initial neural signals (the sensation stage).
Sensation involves simple inputs that must be integrated to form complex perceptual objects.
A significant gap persists between raw sensory input and full perceptual experience.

World experience is inherently multisensory and integrated.
Perception combines information across modalities, even if individual senses have unique processes.
The course applies the \text{Distal Object} \rightarrow \text{Physical Medium} \rightarrow \text{Proximal Stimulus} \rightarrow \text{Perceptual Object} framework to understand brain processing.

Perception is shaped by prior knowledge, expectations, and context, not just raw sensory data.
Historically, figures like Descartes (e.g., inverted retinal image) and Wundt explored how the brain compensates for sensory distortions.
The scientific goal is to understand these perceptual compensations, aiming to minimize the sensation-perception gap.

Perceptual principles are exploited in media (e.g., forced perspective).
Course progression: sensory physiology to high-level perceptual principles.
The Distal Object \rightarrow Physical Medium \rightarrow Proximal Stimulus \rightarrow Perceptual Object (D-M-P-O) framework is central.
Perceptual objects correspond to, but aren't perfect matches of, distal objects; knowledge and context influence this.
The "Hofden step" (sensation-perception gap) is a key concept.
Historical figures (Descartes, Wundt) shaped perception studies.
Rods and cones are primary visual transducers; the D-M-P-O framework applies across senses.
Canonical pathway: D \rightarrow M \rightarrow P \rightarrow O
- D, M, P, O \text{ represent the distal object, physical medium, proximal stimulus, and perceptual object, respectively}.
- Alternate: \text{Distal Object} \rightarrow \text{Physical Medium} \rightarrow \text{Proximal Stimulus} \rightarrow \text{Perceptual Object}
- Visual example: \text{Light energy} \rightarrow \text{retinal receptors} \rightarrow \text{neural signals} \rightarrow \text{percept}.
- Auditory example: \text{Sound waves} \rightarrow \text{hair cells in cochlea} \rightarrow \text{neural signals} \rightarrow \text{percept}.