Visual Perception q's...help!

[littlebecc]

I don't know how to answer this question... i'm just confusing myself..

Question: "A person is shown two lights, one of which is slightly more intense than the other. Even though the two lights are different in intensity, the person may not notice any difference. Explain why this may occur, referring to thresholds in your answer"

Thanks in advance!

[ed_saifa]

For the visual system to detect a stimulus, a minimum amount of energy is required. This is defined as the threshold value. The ganglion cells have a particular threshold value that is needed in order to produce a response. For there to be discrimination between intensity of light, unequal numbers of ganglion cells must be stimulated. 

[Chromeo33]

The person's differential threshold does not account for and is not able to pick up the different intensities between the two visual stimuli?
Not too sure..
If someone were to have a weak diff. threshold compared to a person with a strong diff. thershold, who can perceive differences in stimuli better? I'm getting confused too!

[littlebecc]

Thanks ed_saifa! I wrote something similar along those lines

[Visionz]

ed is wrong, when it comes to VCE psych.

You wont get full marks unless you mention differential threshold/just noticeable difference. The change is likely to be within this threshold and therefore she cannot see it.

[Nullisecundus]

visionz is correct; the threshold you're looking for is the differential/just noticeable difference threshold