Science desk
< June 10	<< May | June | Jul >>	June 12 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

In the Valley Water ad which exhorts you to "Bring your yard to life!", did I correctly identify the butterfly at the top right as a Papilio machaon? (Which, BTW, would be a pretty weird choice of species for them, given that it's not native to the area!) Pictures are OK if needed to answer the question, but keep them small! 2601:646:8082:BA0:15AB:5FDE:33D5:2ED4 (talk) 11:37, 11 June 2025 (UTC)[reply]

What ad are you referring to? Matt Deres (talk) 13:41, 11 June 2025 (UTC)[reply]

Presumably this one. Mikenorton (talk) 13:54, 11 June 2025 (UTC)[reply]

I think that image of the ad is too small for a positive ID, but maybe Papilio zelicaon, which is "native to the area"? Deor (talk) 14:04, 11 June 2025 (UTC)[reply]

A better version of the image here - looks like P.machaon. Mikenorton (talk) 14:07, 11 June 2025 (UTC)[reply]

Why do people scratch their heads when they are trying to solve a puzzle or difficult question? 2A00:23C7:533:3C01:C50D:1C:C26D:B845 (talk) 18:36, 11 June 2025 (UTC)[reply]

Do you? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:46, 11 June 2025 (UTC)[reply]

Not since I was in infants school, I think. But my nephews do. 2A00:23C7:533:3C01:C50D:1C:C26D:B845 (talk) 20:04, 11 June 2025 (UTC)[reply]

A response to some level of anxiety, maybe? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:30, 11 June 2025 (UTC)[reply]

See Displacement activity. {The poster formerly known as 87.81.230.195} 94.6.40.15 (talk) 22:51, 11 June 2025 (UTC)[reply]

The article describes the phenomenon ("what?") and the conditions triggering it ("when?"), but does hardly explain it ("why?").

Additionally, I think that head-scratching while considering difficult problems is not constrained to having to make a difficult choice. In fact, it is IMO more likely when the thinker does not even know where to start and needs to organize their thoughts to get a grip on the problem.  ​‑‑Lambiam 00:42, 12 June 2025 (UTC)[reply]

I see this in the form of slow tail wagging in cats during decision making when they are faced with the always-on-the-wrong-side-of-a-door conundrum. I've wondered whether it is something like a way to inject a noise signal into competing neural patterns to do something or other, like enhance differences, speed up resolution. I guess this is testable. Does decision making time or reliability change for tricky questions/choices when people are exposed to a stimulus (like white noise, automated head scratcher or whatever). But since I've only had about 2 original ideas that panned out in my life, I assume someone has already thought of this and tested it. Sean.hoyland (talk) 05:03, 12 June 2025 (UTC)[reply]

I'm very sorry to admit that I've just found this at the Daily Mail: "Why we scratch our heads when we're confused". It was a 2017 study by a Jamie Whitehouse from the University of Portsmouth who looked at why macaque monkeys scratch their heads in certain situation. It was published in Scientific Reports. Martinevans123 (talk) 13:29, 12 June 2025 (UTC)[reply]

Is the Daily Mail claiming that we evolved from ape ancestors? What happened to them? Anyway, here's a more recent interesting paper from Whitehouse et al. Sean.hoyland (talk) 15:15, 12 June 2025 (UTC)[reply]

Yes, seems Whitehouse is now at Nottingham Trent University. Martinevans123 (talk) 15:46, 12 June 2025 (UTC)[reply]

The Trier social stress test sounds very effective, although very arbitrary. Participants must prepare for a clinical psychologist job interview, including a 3-minute speech about why they are an ideal candidate. Our article says "The participant is allowed to use paper and pen to organize their presentation, but this paper is then unexpectedly taken away from them when it is time to begin the presentation." ... participants are given a series of purposefully difficult job interview questions (e.g. ‘What do you consider to be the main advances in the area of Clinical Psychology in the last 20 years?’) and then they have to count backwards in 13s from 1022.  Card Zero  (talk) 20:39, 12 June 2025 (UTC)[reply]

I only scratch my head when it's counting backwards in 14s. Martinevans123 (talk) 08:14, 13 June 2025 (UTC) p.s. I didn't even get the job.[reply]

I think this is the result of gesture learning. When we see adults doing this as children, we imitate this behavior, and after generations of imitation, this habit is reinforced. Stanleykswong (talk) 17:22, 12 June 2025 (UTC)[reply]

I think many adults often do it deliberately, as a kind of self-parody of confusion. Martinevans123 (talk) 17:37, 12 June 2025 (UTC)[reply]

It might be interesting to see the geographical distribution of head-scratching while decision making to see whether it is actually universal. Gaze direction also changes during decision making and the directionality seems to vary across cultures. Sean.hoyland (talk) 11:11, 14 June 2025 (UTC)[reply]

The article analemmatic sundial claims that the Barbate lighthouse is the gnomon of one. It also claims, "The gnomon is not fixed and must change position daily to accurately indicate time of day."

As the lighthouse looks stationary, is one of the claims untrue?

Thanks, cmɢʟee⎆τaʟκ 23:50, 11 June 2025 (UTC)[reply]

It isn't, by definition, an analemmatic sundial. The tower does not move. Instead, there are multiple circles. You pick the circle that matches the current date and use that to tell time. So, instead of moving the tower, they are essentially moving the arc around the tower. 68.187.174.155 (talk) 00:15, 12 June 2025 (UTC)[reply]

It's not the prototypical analemmatic sundial (which has nothing to do with the analemma; it's a misnomer), but it is based on the same principle, namely the intersection of the shadow of a vertical rod with an ellipse on the ground. The difference is that the rod doesn't move, but the ellipse moves (and changes size). Or rather, multiple ellipses are shown on the ground and the user picks the right one for the date. How much one can deviate from the prototypical analemmatic sundial and still call it one is a question that has no scientific answer. PiusImpavidus (talk) 11:03, 12 June 2025 (UTC)[reply]

Thanks for explaining. I'll clarify it in the caption on the article. cmɢʟee⎆τaʟκ 20:40, 12 June 2025 (UTC)[reply]