lecture recording on 28 January 2025 at 20.06.57 PM

Introduction to Sensation and Perception

• Sensation: involves the stimulation of sensory nerves and the initial detection of stimuli from the environment.

• Perception: is the process of combining and interpreting these sensory signals to create a coherent understanding of the world. It is active and influenced by prior knowledge and expectations.

Activity with Miracle Berries

• Starting with giving participants a miraculin tablet, which is derived from miracle berries.

• Effect: The miraculin temporarily alters taste perception, especially making sour tastes (like lemons) taste sweet.

• Duration: This effect lasts for about an hour to an hour and a half but the sensation of sourness remains.

Basics of Sensory Stimulation

• Sensory stimulation involves nerve cells picking up environmental information and sending it to the brain.

• Absolute threshold: the weakest level of stimulus detectable 50% of the time.

• Example of absolute threshold: possibility of detecting the light of a candle from a distance on a dark night.

• Difference threshold: the minimum difference in stimulation that a person can detect 50% of the time.

  • Example: Detected weight increment when lifting – some can detect a single pound, others may need more.

Subliminal Stimuli

• Subliminal stimulation involves stimuli presented below the threshold of conscious awareness, impacting our perception without our realization.

• Example: Studies mention flashes of images to influence consumers without explicit awareness.

• Signal Detection Theory: we need both motivation and attention to detect stimuli accurately, affected by background noise and personal motivation.

Visual Sensation and Processing

• Visual processing begins when light enters through the cornea, passes through the pupil and lens, and reaches the retina.

• The retina contains rod and cone cells:

  • Rods: sensitive to light and dark changes, shapes, and movement.

  • Cones: responsible for color vision, concentrated in the fovea.

• Blind spot: the area in our visual field where no photoreceptor cells exist, where the optic nerve exits the eye. The brain fills in this blind spot with surrounding information.

Color Perception Theories

• Trichromatic Theory: proposes that the human eye has three types of cones sensitive to red, green, and blue light, combining to produce perceived colors.

• Opponent Process Theory: states that color perception is controlled by opposing pairs (e.g., red/green, blue/yellow) and explains color blindness and afterimages.

• Afterimages occur as sensory receptors tire after prolonged exposure to a color, leading to unexpected color perceptions when the stimulus changes.

Gestalt Principles of Perception

• Closure: our brain tends to fill in missing information to form a complete image (e.g., perceiving triangles in gaps of shapes).

• Proximity: objects that are physically close to each other are perceived to be grouped together (e.g., people in a room).

• Similarity: items that look similar are perceived to be part of the same group (e.g., sorted by shape or color).

Conclusion

• Perception is influenced by multiple factors including context, prior experiences, and sensory adaptation.

• Understanding these principles aids in comprehending how humans perceive and interpret their environments.