Moon Illusion

Joshua Warren Author

04/06/2021 Added

51 Plays

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Exploring what causes the moon Illusion

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[00:00:00.520]Hello.
[00:00:01.500]My name is Joshua Warren and this is the "Moon Illusion."
[00:00:06.540]The Moon illusion.
[00:00:07.610]What is it?
[00:00:08.610]Well, you've probably seen it before.
[00:00:09.880]It's the idea that the Moon appears larger near the horizon
[00:00:14.570]than it does higher up in the sky.
[00:00:17.420]And this appears to be a perceptual error,
[00:00:20.550]an optical illusion,
[00:00:21.580]as the Moon size is objectively constant
[00:00:24.300]regardless of its location in the sky,
[00:00:27.120]though it's not definitively known
[00:00:29.740]as to what causes it.
[00:00:32.610]Well, is it really an illusion?
[00:00:34.090]Well, there's ways to prove it by overcoming the illusion.
[00:00:37.190]One way is the hand-telescope
[00:00:39.030]where you can make an O shape with your hand
[00:00:40.780]and look through it, look at the Moon through it,
[00:00:43.070]and you should be able to see
[00:00:44.060]that the Moon looks significantly smaller
[00:00:46.240]even if near the horizon.
[00:00:48.050]And you can also change your perspective
[00:00:49.700]by facing away from the Moon and leaning over
[00:00:52.320]and looking back between your legs at the Moon,
[00:00:54.490]and it should also appear to be smaller.
[00:00:58.950]Now we're gonna talk about some of the theories
[00:01:00.550]researchers have put forth
[00:01:01.800]explaining why the Moon illusion happens.
[00:01:05.790]So the first theory we're talking about
[00:01:07.370]is the apparent distance hypothesis,
[00:01:09.260]which is the idea that our perception
[00:01:11.150]of how far away the Moon is
[00:01:12.660]determines the apparent size of the Moon.
[00:01:15.320]And this was noted in 200 C.E.
[00:01:17.030]by Greek and Islamic astronomers.
[00:01:19.620]And there are multiple competing versions of this theory,
[00:01:22.060]but it's still the most popular theory
[00:01:24.210]as to explaining why the Moon illusion exists.
[00:01:26.830]These competing theories are based on
[00:01:28.270]the different processes
[00:01:30.180]on how we perceive the Moon's distance.
[00:01:35.710]So, essentially, this theory states
[00:01:37.440]that our perceptual system responds
[00:01:39.320]as though the Moon is farther away at the horizon.
[00:01:41.950]And this could be due to
[00:01:43.060]more powerful depth cues at the horizon
[00:01:45.290]or a lack of being able to perceive
[00:01:47.630]the Moon's distance from us or from the horizon.
[00:01:51.420]Because the Moon is at objectively a consistent size
[00:01:54.740]anywhere in the sky,
[00:01:56.490]our perceptual system overcompensates,
[00:01:59.600]perceiving it to be farther away at the horizon
[00:02:02.510]and therefore larger.
[00:02:06.240]The next hypothesis is the Ponzo illusion,
[00:02:08.580]which is similar to the apparent distance hypothesis
[00:02:11.190]where some researchers believe that the Moon at the horizon
[00:02:14.720]is perceived to being at the end
[00:02:16.180]of the converging stretch of landscape before it.
[00:02:19.030]This creates the real-world Ponzo illusion
[00:02:21.100]that makes our perceptual systems
[00:02:23.490]interpret the Moon as being farther away.
[00:02:26.070]These cues are absent in a Moon
[00:02:29.280]that is higher up in the sky.
[00:02:31.940]The next theory is the relative size hypothesis,
[00:02:34.470]which is based on the Ebbinghaus illusion.
[00:02:37.400]This is that the perceived size of the Moon
[00:02:40.710]is dependent on the objects around it,
[00:02:42.590]making it seem larger based on the contextual cues
[00:02:45.640]that are much smaller than the Moon is.
[00:02:48.700]While a Moon higher up in the sky
[00:02:50.580]is surrounded by the emptiness of the dark night sky,
[00:02:53.460]making it appear smaller.
[00:02:58.770]So onto our study.
[00:03:00.930]Unfortunately, due to the pandemic,
[00:03:03.340]this year, we focused on exploring
[00:03:05.220]how to develop an online computer study
[00:03:07.640]that will eventually run this coming year.
[00:03:11.370]This will allow us to test far more participants
[00:03:13.690]in a shorter amount of time.
[00:03:15.400]Currently, we're having difficulty controlling for things
[00:03:18.270]like different users' devices, brightness settings,
[00:03:21.530]screen size, screen resolution.
[00:03:24.260]So, unfortunately, we don't have any data right now.
[00:03:27.830]The question we propose, however, is,
[00:03:29.530]what causes us to perceive the Moon
[00:03:31.410]as larger than it is objectively sized
[00:03:33.630]when viewed from the ground?
[00:03:35.890]Because there are so many different theories
[00:03:38.210]that are supported by many different researchers,
[00:03:40.410]we decided to focus on exploring the role context cues play
[00:03:43.890]in perception of the size of the Moon.
[00:03:46.280]We have designed an experiment
[00:03:47.410]that will test size estimate accuracy and conditions
[00:03:50.180]with and without context cues present,
[00:03:52.750]such as objects in the foreground
[00:03:55.260]or environmental stimuli that simulate the Ponzo illusion.
[00:04:00.290]We are working on the following hypotheses.
[00:04:02.570]For experiment one,
[00:04:03.660]which is context cues or the lack of context cues,
[00:04:07.090]we hypothesize that with context cues,
[00:04:09.420]size estimates will be more accurate.
[00:04:11.970]For experiment two,
[00:04:12.980]which is the common perceptual error or the Ponzo illusion,
[00:04:17.390]we hypothesize that either without Ponzo-like cues,
[00:04:20.470]size estimates will be more accurate,
[00:04:22.590]or that Ponzo-like cues exist already,
[00:04:26.110]and so no change in accuracy will occur
[00:04:28.560]with or without the cues.
[00:04:33.110]For experiment one,
[00:04:34.680]in the first set of trials,
[00:04:35.790]participants will be presented
[00:04:37.100]with two identical images side by side,
[00:04:39.550]both depicting a landscape and horizon
[00:04:42.100]and a Moon just above the horizon.
[00:04:44.140]However, in one image,
[00:04:46.210]the size of the Moon will be either bigger or smaller.
[00:04:50.930]First, without context.
[00:04:53.280]This is what they will see.
[00:04:54.710]And they will be asked to use the up or down arrow keys
[00:04:57.900]to incrementally increase or decrease the size of the Moon
[00:05:01.300]until they feel that both Moons are of equal size.
[00:05:04.790]As such.
[00:05:07.670]Then in the second set of trials,
[00:05:09.540]one will contain a context cue, such as this car window,
[00:05:14.170]and then they will be asked to
[00:05:16.970]incrementally increase or decrease the size of the Moon
[00:05:19.520]until they are equal.
[00:05:25.460]For experiment two, in the first set of trials,
[00:05:28.170]participants will be presented with an image of a landscape
[00:05:31.230]with one Moon above and near the horizon
[00:05:33.450]and a second Moon of differing size
[00:05:35.870]will be below the horizon.
[00:05:38.390]As such.
[00:05:40.580]They will be asked to use the up and down arrow keys
[00:05:44.440]to incrementally increase and decrease,
[00:05:45.713]just like the previous experiment.
[00:05:49.440]In a second set of trials,
[00:05:50.273]the image will depict a natural set of Ponzo illusion lines
[00:05:53.320]extended out into the sky.
[00:05:55.540]As you can see, the mountains here
[00:05:57.760]make that sort of valley shape
[00:05:59.640]that is sort of an inverse Ponzo illusion
[00:06:03.780]than what's converging towards them.
[00:06:06.650]Again, they will be asked to use arrow keys
[00:06:08.950]to change the size until they match.
[00:06:11.700]This is just to demonstrate what we're talking about
[00:06:15.410]with these Ponzo illusion lines.
[00:06:20.900]As for what I predict will happen,
[00:06:23.030]in experiment one,
[00:06:24.130]I expect that some of the context cues
[00:06:26.860]may cause inaccurate estimations of the size,
[00:06:30.810]but I don't expect every instance of context
[00:06:33.240]to cause inaccuracy.
[00:06:34.710]I think some of them may have a stronger effect than others.
[00:06:38.420]In experiment two,
[00:06:39.620]I expect to see that the natural Ponzo lines
[00:06:42.590]created by the valleys and mountains
[00:06:44.900]will cause some amount of inaccuracy in the size estimation.
[00:06:50.760]That is the "Moon Illusion."
[00:06:52.230]Thank you.

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