Q10 - Insects can see ultraviolet light

[adarsh.murthy]

I am stuck between D and E here. I think we need to stengthen the causal statement that these insects get attracted to these Glomosus spider webs which reflect UV rays due to the "specific pattern" of the reflected rays and not just because of the fact that they reflect and insects see it. Is this right?

If yes, I dont quite understand why E should be right as it just says that the insect gets attacted to a web that reflects UV rays(the other one has no UV) and no mention about the fact they do get attracted due to the "specific pattern" that Glomosus webs reflect. Thanks for help here!

[timmydoeslsat]

You are right that we are looking to strengthen the causal conclusion.

The causal conclusion is that the probable reason of insects being attracted to the Glomosus spiderwebs is the reflection of UV light.

This conclusion stems evidence that insects can see UV light. We know that this UV light can be useful to them.

However, we do not what the cause is of this attractiveness. Perhaps these webs offer protection of some sorts. We do not know the cause.

The stimulus is attempting to use the fact that insects can see UV light and benefit from UV light reflections, to assert a cause of them being attracted to the spiderwebs.

How can we try to strengthen cause? Well, we can attempt to eliminate other variables that may account for cause.

Answer choice E gives us a wonderful hypothetical. Imagine 2 Glomosus webs being placed in front of the fruit flies. One is has UV light and the other one does not.

The majority of the flies went to the UV light web.

This strengthens the idea that the UV light is the cause.


Answer choice D does not strengthen our causal conclusion. We are trying to strengthen the idea that the UV light is the cause of attraction, while this answer choice gives us two webs that both have UV light. This cannot strengthen our causal claim of UV light being a factor, as it is present in both webs.

[noah]

Great write-up, Tim! I'm putting in a discussion of the other wrong answers. While I know we can call this a "causal" issue, I specifically think of this as an "explanation argument." That means we learn about a phenomenon and then the conclusion is an explanation. What often weakens such an argument is another possible explanation. What strengthens it is often showing that other explanations aren't true. In this case, the strengthener is a solid piece of experimentation showing that the specific factor cited is actually causing what we're suggesting it does (i.e. it's not something other cause, that we haven't thought of).

You are right that we are looking to strengthen the causal conclusion.

The causal conclusion is that the probable reason of insects being attracted to the Glomosus spiderwebs is the way it reflects UV light.

This conclusion is based on evidence that insects can see UV light, and the fact that this UV light can be useful to them.

However, we do not what the cause is of this attraction to UV light. Perhaps these webs offer protection of some sorts. We do not know the cause for sure, and we don't care.

The stimulus is attempting to use the fact that insects can see UV light and benefit from UV light reflections, to assert a cause of them being attracted to the spiderwebs.

How can we try to strengthen cause? Well, we can attempt to eliminate other variables that may account for cause.

Answer choice E gives us a wonderful hypothetical. Imagine 2 Glomosus webs being placed in front of the fruit flies. One is has UV light and the other one does not.

The majority of the flies went to the UV light web.

This strengthens the idea that the UV light is the cause.

(A) simply tells us that some other webs don't reflect UV light. But, the argument is about a specific web that does. Out of scope.

(B) tells us that a different type of silk also reflects UV light. This perhaps was tempting if you added a lot of ideas--"well, if all types of silk reflect UV light, then it has nothing to do with webs and catching insects, thus the reflective quality is not intended for..."--and we shouldn't have to work so hard to make an answer choice work!

(C) is about another type of spider. Out of scope.

(D) might actually weaken the argument! If flies chose the Glomosus web even though another web also reflected UV light, then apparently there's something else that is attracting them.

And, my last point, to the OP (original poster), you're smart to have noticed the specificity of the conclusion - it's about the specific pattern! - but simply reflecting the light is part of the phenomenon. So, the experiment cited in (E) blocks out other factors, and, since the webs used do in fact have this pattern, we can be sure that these patterned reflections were there. Is it possible that the attraction has nothing to do with the specific pattern? Yes. But, we don't need to make the argument 100% valid, we just need to strengthen it.

[adarsh.murthy]

I dont completely agree OR I dont completely understand !

As far as I see, the conclusion is not the causal statement that the probable reason of insects being attracted to the Glomosus spiderwebs is the reflection of UV light BUT instead it is the causal statement that these insects get attracted to these Glomosus spider webs which reflect UV rays due to the "specific pattern" of the reflected rays. For some reason I think the pattern plays a role and not just the fact that the insects see something being reflected.
So if this is true, D would imply that even though the other web reflected UV, it did not form the same pattern of reflected UV as that of the Glomosus web. What am I missing?

[timmydoeslsat]

I apologize for not being more clear. I did intend to state that the causal conclusion is that the insects are probably attracted to the Glomosus webs because of the specific patterns of UV light that the webs reflect.

We need to get down to basics.

We are given a causal conclusion that something is probably the case.

Evidence?

- Insects can see UV light
- Insects can identify important food sources and mating sites based off of patterns of UV light
- Insects are attracted to Glomosus webs

WE WILL HALT RIGHT THERE!

We know that insects are attracted to Glomosus webs. It tells us so. It is evidence, it is a premise. However, do we know why it is the case that insects are attracted to Glomosus webs?

No! The stimulus gives us a best guess in its causal conclusion. The stimulus tells us that it is probably because the Glomosus webs reflect specific patterns of UV light.

That is a jump!

We know that reflections of specific patterns of UV light can be advantageous for insects due to food sources and mating sites being identified by such.

However, we do not know the cause of the attraction to the Glomosus spiderwebs.

Answer choice D tells us that fruit flies were put before a Glomosus web and a synthetic web of a similar pattern. So the UV light reflections, you would imagine, would be similar between the two. Both were illuminated with UV light, and many of the flies went to the Glomosus web.

How anti-climatic! Many of them went? How many is many? Did more go to the synthetic web than the Glomosus one?

Even if more went to the Glomosus one, we still have not strengthened the idea that the reflection of UV light of the specific pattern of the web is what is causing the attraction.

In D's hypothetical arrangement, you would have two webs with similar patterns of UV light being shown.

However, with E, you have a situation with 2 Glomosus webs: 1 with UV light being shown through it and 1 without UV light being shown through it.

A majority went with the web that had UV light being shown through it.

That is strengthening the idea that specific patterns of UV light is probably causing the attraction.

[adarsh.murthy]

Thanks! Excellent break down. I see "many" being problematic now. However, E does not prove that the insects are atracted to the G-web due to a pattern which is what the causal conclusion is saying. even though the majority flew there, it might be that they are attracted to a source which is reflecting UV(irrespective of the pattern) as the other web is not reflecting UV at all as it is not illuminated with UV.
But the "many" maybe 2 out of 1000 probably they were blind and randomly flew to the web. So, I see now why D does not stengthen.

[timmydoeslsat]

Thanks! Excellent break down. I see "many" being problematic now. However, E does not prove that the insects are atracted to the G-web due to a pattern which is what the causal conclusion is saying. even though the majority flew there, it might be that they are attracted to a source which is reflecting UV(irrespective of the pattern) as the other web is not reflecting UV at all as it is not illuminated with UV.
But the "many" maybe 2 out of 1000 probably they were blind and randomly flew to the web. So, I see now why D does not stengthen.

You are correct that answer choice E does not prove that the causal conclusion is true. Answer choice E does strengthen that idea, albeit not prove this idea.

You are not embracing the full idea of a patterns of UV light. The causal conclusion is that the attraction is from the specific patterns reflected by UV light.

E shows the 2 Glomosus webs.

1 Web with specific pattern no UV light illuminated
1 Web with specific pattern UV light illuminated

A majority go to the one with UV light illumination. That does not prove that the patterns reflected by the UV light cause the attraction, but it most definitely strengthens it.

[WaltGrace1983]

So are (A) (B) and (C) just completely irrelevant? They are just talking about what webs reflect UV light or what webs don't without providing any effect of this. We need the effect to strengthen the conclusion! At first, I thought I read the argument completely wrong because the answer choices were so awful.

Please let me know if I am missing something - I just don't understand how (A), (B), or (C) are tempting at all and usually I can put myself in a mindset where I can see what the test writers were doing. I am lost on these... I guess I'd rather be lost on understanding the wrong answers than the right ones though

[christine.defenbaugh]

So are (A) (B) and (C) just completely irrelevant? They are just talking about what webs reflect UV light or what webs don't without providing any effect of this. We need the effect to strengthen the conclusion! At first, I thought I read the argument completely wrong because the answer choices were so awful.

Please let me know if I am missing something - I just don't understand how (A), (B), or (C) are tempting at all and usually I can put myself in a mindset where I can see what the test writers were doing. I am lost on these... I guess I'd rather be lost on understanding the wrong answers than the right ones though

Yes, (A), (B), and (C) are totally irrelevant!

(A) might have been tempting to someone who misread the premises and thought that insects were more attracted to Glosmosus spiderwebs than others. Similarly, (B) might haven been a distractor if somehow you got caught up thinking that insects weren't attracted to the linings/coverings despite the UV light (even though we don't know this!), so therefore the attraction must be because of the specific pattern in the web (as opposed to the linings/coverings).

I'm not entirely sure why someone might be tempted by (C) though! I'm sure I could get very creative and construct something if I really tried. :p

Often times wrong answer temptations are based not just on faulty reasoning, but on actual misreading of the information given. If you did NOT misread the stimulus, then it can very hard to see the likely misreadings.

Moral of the story: I wouldn't be too worried about the fact that you don't think they are tempting!

[btwalden]

I As far as I see, the conclusion is not the causal statement that the probable reason of insects being attracted to the Glomosus spiderwebs is the reflection of UV light BUT instead it is the causal statement that these insects get attracted to these Glomosus spider webs which reflect UV rays due to the "specific pattern" of the reflected rays. For some reason I think the pattern plays a role and not just the fact that the insects see something being reflected.

I completely agree. I would never have considered E a possible choice because it just restates the background before the actual argument. We already know they are attracted to the Webs that reflect UV, the argument is about why.

Answer D is about the specific pattern vs a similar pattern, and while not perfect, it seems like the only choice that is relevant to the argument.