Question

1.Describe an experiment you would perform to determine if a beetle can discriminate between green and yellow. Be sure to explain the independent and dependent variables of your experiment.

How might you go about ensuring that your test subjects in the experiment above are attending to the cues you are presenting, and are provided enough motivation to discriminate?

Answer 1

If I set up an experiment in my lab, first I will select at around 40 beetles of the same species. Then I will divide them in two groups and train each group in one condition- in one monochromatic light. One groupgr will train in the wavelength of green zone and one group will be trained in the wavelength of blue zone for almost 2-3 weeks to accommodate them only to that wavelength. Then I will set two target zones for the beetles. One target will be focused with only blue and another with only green.

1st experiment:

Now start the experiment with green accommodated beetles and leave them for target. All the beetles will go for green target. In 2nd set up I will finely tune the blue Target's source of light to increase it's wavelength to 10 lambda and watch the movement of the beetles from the start. Do this experiment with similar wavelength interval to increase it up to green. At the last I will see that beetles will be equally distributed to the two targets because now both are green.

2nd experiment:

Now start with blue accommodated beetles and change the wavelength of the green target to make it up to blue with a 10 lambda of decrease each time.

This will be my experimental set up.

• The independent variable of my calculation for above experimental set up will be wavelength. And dependent variable will be the number of beetles in the "target where wavelength is changing."

To ensure that the test subjects are only attending the cues I'm presenting and not the external ones, I can do the experiment in complete darkness to eliminate visual cues and to make them phototactic during training. I should also eliminate chemical cues or targets must contain similar chemical cues. And to eliminate gravitational cue I can set up the experiment in a wooden box and position in such a way to eliminate the gravitational cues. And these must be ensured during training.