Sensory Thresholds and Perception

Absolute Threshold

• Lowest intensity of a stimulus detectable.
• Under ideal conditions, human senses have very low absolute thresholds (e.g., seeing a candle flame at $30$ miles).

Noise

• Irrelevant and competing stimuli that hinder accurate detection of specific stimuli.
• Can be any distracting input, not just sounds.

Difference Threshold (Just Noticeable Difference - JND)

• Smallest difference between two stimuli required for detection $50$ percent of the time.
• Increases as a stimulus becomes stronger (e.g., a small volume change is more noticeable when music is soft).

Weber's Law

• States that two stimuli must differ by a constant proportion to be perceived as different.
• Example: Adding $1$ candle to $20$ candles is noticeable; adding $1$ candle to $120$ candles is not, but a higher proportion would be.