A research participant can just discern the difference between 50 and 51 candles burning in an otherwise darkened room. According to Weber's law, how many lit candles would have to be added to 300 already-lit candles before a participant could just notice the difference in illumination?

Question

Quizplus · Accepted Answer

According to Weber's law, the difference threshold (the minimum amount of change needed to detect a difference) is a constant proportion of the original stimulus. In this case, the difference threshold is one candle (51 - 50). To apply Weber's law to the scenario with 300 already-lit candles, we need to calculate the proportion between the difference threshold of one candle and the original stimulus of 50 candles. This gives us: 
1/50 = x/300 
Where x is the number of additional candles needed to reach the difference threshold with 300 already-lit candles. Cross-multiplying and solving for x, we get 6. Therefore, six additional candles would have to be added to 300 already-lit candles before a participant could just notice the difference in illumination.

A Research Participant Can Just Discern the Difference Between 50