WEBER’S LAW AND SENSORY ADAPTATION Maneesha Ram Sanita Boparai

Difference Threshold  the minimum amount of difference between two stimuli so that a person can be able to detect the difference

Example:  You are watching TV, but your parents are having a discussion and you can’t hear the TV; you turn it louder, but you still can’t hear the TV (because it has not met your difference threshold); so you turn it louder again until you can hear the TV (because it has met your difference threshold)

Weber’s Law  the principle that, two stimuli must differ at a minimum percentage to be perceived as different  Here are the minimum percentage differences for each type of stimuli:  Light 8%  Weight 2%  Tone 0.3%

Matching Activity  Light – 60%  Sugar – 10g  Textbook - 3  Chime – note: D  Star – large  Guitar – note: B  Bowling ball – 15Ibs  Textbook – 10  Chime – note: G  Bowling ball – 5lbs  Guitar – note: A  Sugar – 100g  Light – 80%  Star – small

Sensory Adaptation  Diminished sensitivity as a consequence of constant stimulation After a constant exposure to a stimulus, the nerve cells in the body start to fire less

 You jump into a swimming pool, you begin to shiver because of the cold water, but soon you become used to it.  You’re visiting your friend’s house and when you walk in, you notice a smelly odour. You can’t stand it at first, but after a while you stop noticing the smell Example:

Interactive Activities  Perfume: Can you still smell the perfume we sprayed at the beginning of our presentation?  Silent Ball (Light room vs. Dark room)