Q1 - Marmosets are the only primates

[mrudula_2005]

Obviously E best supports the hypothesis here, but doesn't D as well? I feel like the response would be "well humans don't matter when it comes to Marmosets"

But, if humans are the ONLY other primates that display a preference for using one hand rather than the other, then I feel like their behavioral patterns bear SOME significant and could certainly support a hypothesis regarding the other primate that shares that behavior.

That being said, if, as the answer choice suggests, humans also evidence a pattern in which offspring reared by left-handed parents generally share their parents' handedness, does that not support the researchers' hypothesis?

Or is it off because D's "those who are left-handed are likely to have at least one left-handed parent" does not necessarily mean that it is by imitation that these humans have learned to use the left-hand. (although the same jump is made in the stimulus as well).
OR does it go off because D only discusses the patterns in left-handed humans so even if they DID prove some kind of imitation, it could just be limited to the left-handed humans and doesn't explain in a rounded way that it is by imitation that humans in general (both left handed and right handed, both the minority and the majority) learn which hand to use?

thanks!

[giladedelman]

Great post! All the suspicions you raised are indeed reasons why (D) is incorrect.

The core looks like this:

Marmosets engage in much imitative behavior, and those reared by left-handed parents tend also to be left-handed. THEREFORE, infant marmosets learn which hand to use through imitation.

(Notice that the "hypothesis" is supported by a premise and so is just a conclusion in disguise.)

Now, we're looking for something that would strengthen the argument that marmoset handedness is learned through imitation, rather than passed down genetically.

(E) is correct, because if exposure to right-handed adults to whom the infants are unrelated results in greater incidence of right-handedness, then it follows that this behavior is learned through imitation, rather than genetically influenced.

Let's run through the other answers before dealing with (D).

(A) is basically a premise booster. We're told that more marmosets are left-handed than right-handed. Since "many" just means "some," this answer is just telling us that some adult marmosets are righties, which we already knew.

(B) seems to run against the hypothesis. Shouldn't most marmoset siblings prefer the same hand, since they're imitating the same parents?

(C) is out of scope. We're interested in where hand preference comes from.

All right, now let's talk about (D). By far the biggest problem with this answer is the first one you identified. The argument is unambiguously about MARMOSETS. So the fact that this answer is about humans is reason enough to chuck it. The point you made, that humans' "behavioral patterns bear SOME significance and could certainly support a hypothesis regarding the other primate that shares that behavior," is waaaay too big a leap to make on the LSAT! Where does the argument say that analogous behaviors across primate species can be expected to have analogous causes?!

Now, even if we accepted the human-marmoset link, which we should not, we'd run into the second issue you raise: this answer doesn't address whether handedness is the result of imitation. That lefty humans tend to have a lefty parent doesn't mean they imitate that parent; handedness may be genetically heritable.

All right?

[Abeckham13]

I also choose D rather then E though these two were my only remaining contenders

Now, we're looking for something that would strengthen the argument that marmoset handedness is learned through imitation, rather than passed down genetically.

Where in the stimulus does it imply that marmosets learn from imitation rather then genetic? Or is it something that can be implied and I just tunnel visioned in the stimulus too hard?

Secondly, E says that Marmosets are "more likely to be right handed if they are raised in captivity with right handed adults to whom they are not related".

"More likely" threw me off because it didn't completely imply imitation like the hypothesis asserts. If the argument asserts something absolutely occurs, then how does something that says it's "more likely" to occur strengthen it?

If we throw in the rather then genetics part it becomes even more complex. A baby marmoset raised in captivity being "more likely" to be right handed rather then left handed does not argue that marmosets absolutely learn through imitation rather then genetics. Just that they have an increased likelihood.

[VendelaG465]

Isnt one way to strengthen an argument by referring to another experiment that had the same results? At first i saw D & thought out of scope since we were discussing marmosets but then i figured even tho we were discussing humans it still had the same concept, being raised in a household with at least one left handed parent produced a left handed child?

[ohthatpatrick]

Yes, we could say (D) does more than nothing, but barely.

To strengthen a causal hypothesis, you need to either:
1. RULE OUT a different explanation for the same observed fact
or
2. INCREASE the plausibility of the author's explanation

Here, we'd be thinking
"I need an answer that rules out a different way of explaining why more marmosets are left-handed" or "I need an answer that bolsters the idea that marmosets get their left handedness through imitation."

You can increase the plausibility of an explanation by discussing other examples / studies in which something similar transpires.

So we could say that (D) slightly bolsters the plausibility that marmosets get their left-handedness through imitation, since in humans it seems that left-handed kids usually have left-handed parents, but it's not a strong answer.

The alternative explanation we should probably be considering for how marmoset kids get their left-handedness is that left-handedness is something genetic, not learned.

If that's in your brain, then (D) really seems to do nothing, since we still wouldn't be able to tell whether left handed humans got it by IMITATING their parents or by HAVING GENETIC SIMILARITY to their parents.

(E) rules out the possibility that they're getting their left-handedness via genetics, because marmosets match their parents handedness even when they're "adopted' parents with different genes.

Hope this helps.