| ABSOLUTE THRESHOLD | The minimum amount of stimulation that can be detected on a sensory channel (e.g. ad copy may be brilliant but if on a sign that can't be seen it's wasted) |
| DIFFERENTIAL THRESHOLD | The ability of a sensory system to detect changes or differences among stimuli (=JND) |
| JND: Just Noticeable Difference | The minimum change in a stimulus that can be detected by a perceiver |
| WEBER'S LAW | The principle that the stronger the initial stimulus, the greater its change must be for it to be noticed |
The concept of JND (Just Noticeable Difference) can be illustrated in Spot the Difference Games. The viewer is given one picture and asked to "Spot the Differences".
If when you first look at the two picture you see no immediate visible difference, what does that say about Just Noticeable Difference?
Once you know the differences, what does that say about what you now perceive on looking at the pictures again. Can you "unknow" the differences? What implications would this have for a marketer who was trying to make slight unnoticeable differences to a product that are later pointed out by consumers?
The two pictures below have 5 differences. Can you spot them?
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To view the answer, put your mouse on the man above.