Lecture Notes: Absolute Threshold of Sensation

Key Concepts

Definition: Minimum intensity of a stimulus needed to detect it 50% of the time.
Importance of the 50% clause:
- Individual Differences: Different individuals may perceive stimuli differently at low levels.
- Intra-individual Differences: Variations in an individual's perception of stimuli at low levels.
Practical Example: Sound detection tests in schools using headphones.
- Percentage of Correct Detections vs. Intensity of Sound.
- 50% mark on the graph represents the absolute threshold.

Definition: Smallest difference in stimulation that can be detected 50% of the time.
Example: Adjusting a dimmer switch on a light and noticing a change in brightness.

Psychological States: These can affect the absolute threshold.
- Expectation: Awareness and anticipation of a text message.
- Familiarity: Recognition of specific vibrative sounds from your phone.
- Motivation: Desire to receive an important message may heighten detection.
- Alertness: Greater likelihood of detection when fully awake.

Definition: Stimuli below the absolute threshold, not detectable 50% of the time.
Example: Subliminal messages, which are below the threshold of sensation.

Absolute threshold is not fixed and varies due to psychological factors.
Different from the difference threshold, which focuses on detecting differences in stimulus intensity.

These concepts help us understand the mechanisms of sensory detection and variation in human perception.