Q18 - Psychologist: Birth-order effects

[shirando21]

I skipped this one under timed practice.

I still have difficulties when I review.

Can anyone go through this question, please?

Thank you very much.

[schmid215]

The key assumption in the argument is that the standard personality tests are an effective method of determining whether or not there are birth-order effects, and studies based on the impressions of relatives are not. Negating (A), we can see how it would destroy the argument, because the negation of (A) entails that standard personality tests will never find birth-order effects when they do exist, from which it follows that the standard personality test in question either did not detect those that did exist or only by happenstance was correct; either way, the argument is made unsound by virtue of the fact that it concludes that they do not exist on the basis of an unreliable method

[rinagoldfield]

Hey schmid215, great job explaining why (A) is correct.

The argument core here has a two-part premise leading to the final conclusion. We can break it down like this:

Studies that are based on standard personality tests don’t detect birth order differences among adults

+

Studies that are based on parents’ and siblings’ accounts of a subject’s personality do detect birth order differences

Therefore...

Birth order has no lasting effect on personality, but only effect how a sibling is perceived

The big assumption here is that standard personality tests offer an accurate view of a person’s personality, while reports by his or her family don’t. The author assumes that the views of parents and siblings constitute mere perception, while personality tests offer objective reality.

The question stem asks "Which one of the following is required by the psychologist’s argument?" In other words, we are being asked to find a necessary assumption_ something that MUST be true for the argument to hold.

(A) is correct. This answer choice tells us that standard personality tests accurately capture the effects of birth order on personality. The psychologist needs this assumption to make his argument.

If you are unsure whether or not an assumption is necessary, try negating it; the argument should collapse when a necessary assumption is negated. In this case, imagine if we said that standard personality tests CAN’T detect the effects of birth order on personality. If this were true, the studies cited by the psychologist would be useless, and the argument would come crashing down. So we know we need to hold onto this assumption.

(B) offers a reason why parents’ and siblings’ accounts of a subject’s personality might be untrustworthy. While this reason could support the psychologist’s argument, it is not required. We only need to know that family members’ reports are inaccurate, not the precise reason why. Eliminate this assumption as unnecessary.

(C) is similar to (B); again, we don’t need to know the exact reason why family members’ perceptions can’t be trusted.

(D) seems to call the premise into question. Didn’t standard personality tests fail to detect any impact of birth order on personality? However, this answer choice concerns the effects of birth order on young children, while our argument core concerns potential LASTING effects of birth order on adults. This answer choice is out of scope.

(E) weakens the argument by negating one of its assumptions. Toss this answer choice.

[tutordavidlevine]

Actually, wouldn’t E be incorrect not because it weakens the argument (as you say), but because the accuracy of the perceptions is out of the argument’s scope? The conclusion states that the birth order affects how a behavior is perceived, not how accurately it is perceived.

[jm.kahn]

Why is A required for the argument when the argument is only about the adults?

A is about all tests including the ones on children and adults. So it's sufficient but not necessary.

[JoyS894]

Could someone help clarify what this argument is really saying? In regards to previous posts, I am not seeing how the argument is stating anything about the accuracy of personality tests or arguing that standard personality tests are more accurate than observations of family members. Clearly, I am missing something, which is why A still doesn't seem to be correct to me. Thank you in advance!

[snoopy]

Could someone help clarify what this argument is really saying? In regards to previous posts, I am not seeing how the argument is stating anything about the accuracy of personality tests or arguing that standard personality tests are more accurate than observations of family members. Clearly, I am missing something, which is why A still doesn't seem to be correct to me. Thank you in advance!

The psychologist is concluding that birth order has no effect on personality since 1) standard personality tests haven't detected birth order in personalities, and 2) the parent/sibling study is subjective ("birth order affects...how a sibling's behavior is perceived.") So, even if parents and siblings have 100% accurate perceptions, the psychologist isn't relying on how accurate their perceptions are because the psychologist claims that birth order merely affects perception, not personality.

i.e Say I take a standard personality test like Myers Briggs and get ENFP (spontaneous, free-spirited, etc). No indication of my birth order. My youngest sibling thinks I'm bossy and controlling because I'm the oldest. Maybe I am, maybe I'm not. His perception might be 100% accurate. Maybe I'm sometimes bossy. But, according to the psychologist, birth order doesn't impact my personality indicated by the standard personality test (Myers Briggs), just how my brother perceives me.

Hence, the psychologist is relying on the accuracy of standard personality tests in measuring birth order, not the parent/sibling study, to make his/her conclusion. A defends the underlying assumption that standard personality tests do detect birth order.

[ldfdsa]

E is tricky. IF the perceptions of family members are accurate, then the argument can't hold. E is weaken the argument as previous post said.
IF E is changed from 'accurate" to "inaccurate" then, it is assumed by the argument.

The core is: standard tests finds no Birth-order effects; sibling reports find Birth-order effect --> there is no Birth-order effects.
two assumptions: standard tests are accurate, sibling reports are not accurate.

[HughM388]

Scientific studies have found no evidence of unicorns, while myths and legends about unicorns don't depict reality but merely the perceptions and unconscious desires of primitive peoples. Therefore unicorns don't exist.

(A) Scientific studies would find evidence of unicorns if unicorns did exist.

[AbhistD667]

Is "the way subject behavior is perceived doesn't have a lasting effect on subject's personality" also a necessary assumption for this argument? This is what I came up with while I read the argument.

[GolddiggerF208]

I spent time eliminating (E) and realized that it is not necessary simply because no matter how accurate or inaccurate, we can still reach that their family perceives the personality.

[Laura Damone]

@AbhistD667, absolutely. Great prephrase. If the perception of your sibling's did impact your personality in a lasting way, that would destroy the argument. Your prephrase passes the negation test, and is therefore necessary. Well done!

@GolddiggerF208, be careful there. You said, correctly, that "no matter how accurate or inaccurate, we can still reach that their family perceives the personality." This sounds to me like an attempt at the negation technique. If it is, you'll want to tweak it a bit, because whether or not we can reach that the family perceives the personality is actually irrelevant. The negation of the answer must be shown to not kill the conclusion of the argument, and this argument concludes that birth order doesn't impact your actual personality. The negation technique for (E), then, should read: "no matter how accurate the perception of parents and siblings, we can still reach that birth order has no lasting effect on your personality."

Hope this helps!