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 vs. Perception

• 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.

Types of Sensation

• 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.

The Link Between Sensation and Perception

• 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.

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.

Limitations of Sensation

• 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).

Limitations of Perception

• 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.

Visual Sensation: Mechanism

• 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.

Visual Sensation of Color

• 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.

Practical Application of Color Sensitivity

• 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).

Conclusion

• 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.