#19 - Light is registered in the retina when photons hit

[kingivory76]

Emily,

Thanks for your reply. I guess at some point we have to just learn things the way they are and can't always have things changed to the way we think they should be! And yes, I am starting to come to the realization that even though I have considered myself having a strong foundation in formal logic, without a proper prep course such as the ones offered by PowerScore, I would have been completely clueless on LSAT test day.

[aec2j]

Hi--simple question on this. Why is it OK to assume we are talking about animals' retinas as opposed to humans'? When I answered this question, I immediately ruled out those answers that included this information. I realize humans are animals, but it seems like an introduction of new info to me given the stimulus did not specify animals and seems like a stretch for the umbrella concept (lion=animal).

[Adam Tyson]

Interesting question, aec2j - mind if I turn it around on you for a moment? What makes you think we are talking about humans' retinas here?

Two things to note here that might help you some. The first is that, yes, humans are animals - this is an idea that is tested frequently on the LSAT (much like the concepts of direct vs inverse proportions, discussed here previously). You are expected to know that any claim made about animals generally applies to humans unless otherwise noted.

Second thing is that this stimulus is entirely general. It is about vision, retinas, photons, rhodopsin, all in the most general of terms. We can't assume that it refers only to certain animals, or to humans, or even that it is limited to earthlings. We might be able to draw conclusions about Martians based on this, if we were to learn that they, too, have retinas and rhodopsin.

So, the introduction of "animals" here is not new information, as long as you accept from the start that we are talking about an anatomical system found in animals (as opposed to, say, rocks and trees, which only have retinas in scary movies and children's tv shows, I think).

The more important lesson to take away here is probably the first one - it's never about "animals as opposed to humans" because humans are animals. That is a standard concept found throughout the test (and in the real world - just ask any vegan, or any scientist for that matter), and while we might sometimes feel bruised egos when we think that we are being put in the same category as mice and lemurs and hippos, we have to put those egos aside and accept that we are all in this thing together. Except for the LSAT, that is - lemurs almost never take this test. Lucky lemurs.

Good luck, fellow animal!

[aaraya]

I, like many before me, fell prey to being confused by "direct proportionality." Looking at the dates from this thread, I'm wondering why this question remains in the LRB Must be true practice set. I've run into a handful of questions difficult for me in the practice sets of the PowerScore curriculum where I search for questions in these forums and the response from PowerScore will usually be something to the effect of "the reason you got this question wrong is because it involved some notorious LSAT vocabulary that you haven't encountered yet. But hold on, you'll get there!" Wouldn't it be easier to include that vocab earlier on in the curriculum, or refrain from using questions with advanced vocabulary in earlier chapters? Or maybe even include an index at the end of the books so I can find the term "direct proportionality?"

[Francis O'Rourke]

Hi Aaraya,

My 2016 edition of the Logical Reasoning bible provides what amounts to a definition in the explanation of this question on page 138. If you have the 2017 edition, I believe it will appear on or around page 127:

... directly proportional to the temperature of the retina (Meaning that when temperatures are lower, molecular motion is lower; when temperatures are higher, molecular motion is higher)...

It is often hard to say what vocabulary is "advanced." When dealing with an economics stimulus, some of my students need a explanation of what inflation is, while others will consider the concept to be elementary. In any case, if you look at the explanations in the book, we try to be as broad as possible in considering what background knowledge test-takers will have.

We do include distinct vocabulary lists and/or explanations for conditional relationships, causal relationships, numbers and percentages, premise and conclusion indicators, formal logic, and common errors of reasoning in this book. Those are just the ones I can remember off the top of my head.

There is a lot of vocabulary that the LSAT considers to be fair game. To include every single "advanced" vocabulary terms at the beginning of the book would make for an incredibly long and tedious read. To put off presenting questions with any "advanced" vocabulary would limit the questions we could include to a rather small set of questions.

I know it can be irritating when you read "hold on, you'll get there!" when you just spent a half hour or more struggling on a single question. I would just add that every time you struggle with a concept to this extent, understand that you are thoroughly imprinting that new concept into your memory, and you will not overlook it again.

[Dave Killoran]

I, like many before me, fell prey to being confused by "direct proportionality." Looking at the dates from this thread, I'm wondering why this question remains in the LRB Must be true practice set. I've run into a handful of questions difficult for me in the practice sets of the PowerScore curriculum where I search for questions in these forums and the response from PowerScore will usually be something to the effect of "the reason you got this question wrong is because it involved some notorious LSAT vocabulary that you haven't encountered yet. But hold on, you'll get there!" Wouldn't it be easier to include that vocab earlier on in the curriculum, or refrain from using questions with advanced vocabulary in earlier chapters? Or maybe even include an index at the end of the books so I can find the term "direct proportionality?"

Hi A,

Thanks for the question—I appreciate it! Although some indeed have fallen prey to "direct proportionality," there are other reasons for including this problem (including how it uses related concepts to get to the answer). And, to be honest, there's never just a single reason that causes a problem to be included in the book, and that particular phrase in this case wasn't the reason this question was included. Do I like that the term comes up? Yes, but it's more of a minor point in its favor as far as this problem goes.

With your broader question about terms, in some instances it's intentional that I don't mention it earlier. The reason is that there is nothing like seeing it in action for the meaning to have the most impact. And, it's not my goal to maximize performance on problem sets; I'm far more interested in using those sets to teach lessons about the way the test makers think, and to teach certain lessons about things that the test makers do.

If we only did basic questions early on, they would have to be very simple, and thus very easy, and thus not really rewarding to do. I have a feeling that the complaints about taking that path would be much greater! Plus, you really can't define every term on the test in a meaningful way before diving into the problems. It would really bog people down, and I already hear some kickback about the word lists that are there early on. I do take your point about an index with that term though, and I'll look to include one in future editions. Thanks for that suggestion!

There's more to this discussion than I have time to post at the moment, so I may come back and try to flesh out my response to more clearly and comprehensively explain what you are seeing and why. Hopefully, this starts to convey the idea that these problems aren't here because of these terms, but that encountering the unknown in this fashion is actually a plus in my opinion because it helps you get better when it matters, which is during the actual test

Thanks!

[aaraya]

Thank you Francis and Dave for those detailed responses. The explanations regarding why the material is ordered the way it is and why certain questions are used gives me a better grasp of exactly what you expect me to learn from those more advanced/complicated questions.

Alex

[Katya W]

Onto your question: the last sentence of the stimulus states that the amount of molecular motion of the molecule rhodopsin is directly proportional to the temperature of the retina. In other words, the warmer the retina, the more molecular motion there is, and - inversely - the colder the retina, the less molecular motion. This is the essence of direct proportionality: we have a positive correlation between motion and temperature. If the relationship was reversed, the last sentence would have said, "The amount of molecular motion is inversely proportional to the temperature of the retina."

So, if the visual system of the animal matches that of its surroundings, then the molecular motion will be higher when the surrounding temperature (and, hence, the animal's own body temperature) is higher. Given the information presented in the second sentence of the stimulus, the visual system of such an animal would be more error-prone.


Thanks!

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I am writing because I also had an issue with the vocabulary of this question, due to the usage of terminology, and not based on the logical structure of the stimulus.
After reading Nikki's explanation, and then conducting research, I have to continue to argue that the usage of "directly proportional" is terminology largely used in the scientific and mathematical communities, and not used much elsewhere. Therefore, it cannot be expected to be commonly known that "directly proportional" can only be a positive correlation between temperature and molecular motion. Logically, someone who is not familiar with the usage of this terminology in the scientific and mathematical communities could assume that temperature and motion are definitely proportional, but not that one definitely only increases when the other increases. As anthonycarral states, a person not knowledgeable in the mathematical and scientific usage of this terminology could logically deduce that motion decreases when temperature increases, or it could be vice versa - therefore choosing one direction over the other would be perceived by the test taker as guessing an answer, or adding outside information to the stimulus.
Logically, if this additional clarifying information had been presented in the stimulus, I would have had no problem selecting the correct answer provided. However, without having this information clarified in the stimulus, choosing the correct answer out of the choices provided became a guessing game, as none of the choices could be proven/supported fully by the stimulus without incorporating outside information.

Three years later, but I wanted to say, thank you for speaking up for the non-mathematical/scientific community and giving such a verbose explanation of what we were thinking (directly proportionate could mean high motion=high temperature, or vice versa, high motion=cold temperature) when we had to deal with this question, and how literally none of the answers seemed correct because most seemed to bring in outside information. Thank you.

[180bound]

Hi I am having some trouble with this question. I am reading from the “Bible” explanation where it says “the answer (B) ties body temperature (remember, the retina is a body part…..”. It seems that getting this question correct depends on the assumption that the temperature of the retina can be predictably associated with to body temperature. The reason I stayed away from this answer was because I personally thought this assumption was superfluous because I can think of plenty of body parts that will/could have different temperatures than the body’s core temperature with no predictable association. I’m thinking of hair, ends of long finger nails, your nose skin (if it is cold outside), the skin of your extremities like hands or feet (again, if it's cold outside) etc. Could someone help me with this?

Thanks!

[Adam Tyson]

It seems like you are doing a lot of work there to make answer B wrong, 180bound, rather than looking for indications that it is supported by the stimulus. Is it possible that an animal with a high overall body temp might have a cold retina? I don't know, I'm not a biologist or ophthalmologist, so I suppose that could be true. But does the stimulus offer some support for the idea laid out in answer B? Certainly - it's no big leap to consider that a higher body temp might at least indicate a warmer retina than would a colder body temp in that same animal. Raising body temp overall would probably not leave the temp of the retina unchanged, or diminished - those both sound unreasonable, even if they might be possible somehow. After all, unlike skin and nails and hair, the retina is inside the body (they do expect you to know that), and so is less likely to be cooled by wind and rain and so on. It's cuddled up in our hot little head, all warm and cozy in a blanket of blood and goo!

It's not about an absolute claim, that a higher body temp guarantees that the retina is hot. It's relative - if an animal's body temp increases, you would expect the temp of that animal's retina to also increase, making it more error prone.

Finally, remember that this is a Most Strongly Supported question, a "soft" variant of Must Be True, so the answer does not need to be perfect and guaranteed. It only needs to be the one answer that gets the most support from the stimulus. Typically the wrong answers get zero support and are easy to eliminate for that reason, and the correct answer, while it may not be perfect, will at least be a reasonable inference to make under the circumstances. Apply that standard to answer B and it should be much more acceptable to you, despite those outlier possibilities. Don't try to find fault with an answer, but instead find evidence that supports it! Wrong answers are wrong all on their own, without any need to think creatively about them.