Psy 02.24.25

Overview of Development

Development involves cognitive, physical, and social changes across the lifespan.
Experience plays a crucial role in development.
Key concepts: sensation and perception—understand their differences and connections.

Sensation: Process of converting sensory information into neural signals.
- Not merely about detecting stimuli but involves initial processing.
Perception: Takes sensations and makes them available for cognitive processing, allowing us to recognize and understand stimuli.
Both processes are active and dynamic, functioning together to interpret external information.
This presentation will primarily focus on visual sensation and perception.

Many kinds of sensations exist; for the discussion, we will focus on vision.
Proprioception: Awareness of body part positions without visual cues.
Balance Sensation: Another unique sense contributing to overall sensory experience.

Sensation and perception are often seen as distinct yet interrelated processes.
Active Processes: Both involve the brain interpreting incoming stimuli.
Cognitive Schemas: Pre-existing knowledge helps the brain process sensory input, known as top-down processing.

Example: Recognizing different visual representations of the same letter (like 'A').
Our brain categorizes inputs based on visual schemas rather than just perceptions of the visual images.

Sensation has inherent limitations in detecting stimuli:
Types of Limitations
- Out of Range: Certain stimuli are not detectable due to biological limitations (e.g., ultraviolet or infrared light).
- Intensity Limitations: Weak stimuli may not be perceived; requires a certain strength for detection.
- Temporal Limitations: Rapid stimuli may go unnoticed; visual stimuli require a minimum duration for detection (around 1/10 of a second).

Not everything sensed is perceived.
- Example of Inattentional Blindness: Focusing on one task can lead to missing other important stimuli.
- Humans struggle with multitasking, contrary to machines designed for parallel processing.

Light projects onto the retina, activating photoreceptor cells: rods and cones.
- Rods: Detect light versus dark, critical for night vision.
- Cones: Responsible for color detection and detail.
The optic nerve transmits visual information to the thalamus, the brain's central sensory hub.

Color perception relies on detecting three primary colors: red, green, blue.
The brain also utilizes contrasting colors to enhance sensitivity, e.g., heightened detection of black when observing white backgrounds.

Example: Walking in snow, visual perception of subtle contours improves after focusing on a bright white surface.
Natural selection favored sensitivity to color contrasts, beneficial to early humans for survival (e.g., spotting camouflaged prey).

The processes of sensation and perception are vital for interacting with the world around us.
They are complex, active processes with inherent limitations influencing our understanding and responses to stimuli.