Cool Visual Illusions: The Margaret Thatcher Illusion

I was reminded of this illusion by the Seed Daily Zeitgeist yesterday. In order to get the full effect, I'll show you one set of photos here, and the rest of the post will be below the fold. The first are from Schwanginer et al. (2003)1:

i-4cc8f427023f64366457fd157562cc73-ThatcherIllusion.JPG

They look pretty normal, right? Now look at these:

i-4e1f67c1d06ecf2a12bb7c8a4b6ae600-ThatcherIllusion2.JPG

Gross, right? Those are the same two photos (the one on the right is now on the left, but rightside up this time. The distortions to the one face, which didn't look so bad when it was upside down, now look... grotesque. What's going on here? Well, in the inverted photo on the right (on the left when the faces are rightside up), the mouth and eyes are upside down. This doesn't bother us all that much when the faces are upside down. In fact, we often don't even notice it, and the expression looks pretty close to the normal face. Only when we view the face rightside up do the upside-down facial features strike us. The illusion is often called the Thatcher illusion, because its discoverer, Peter Thompson2, used a photo of Margaret Thatcher in his original experiment. Here are his photos (from this site):

i-04c396b4410d5d3ae1d62505598c1f44-ThatcherIllusion3.JPG

Why does this occur? Clearly, our ability to process faces is impeded by inverting them, but what exactly is impeded in the Thatcher illusion? There are three competing hypotheses3. The first, called the expression hypothesis, goes as follows4:

(a) the grotesque appearance of a Thatcherized face is due to its expression, (b) inversion impairs the encoding of expression, and, therefore, (c) inversion disrupts the perception of grotesqueness of a Thatcherized face. (p. 284)

In other words, we have a harder time encoding expressions when faces are inverted, so we don't notice the problem with the expressions until we turn the faces rightside up.

The second hypothesis has to do with reference frames. It says that when we view an object like a face, we use two reference frames, one of which is based on the object, and the other on our egocentric or contextual sense of orientation (e.g., what's up and what's down). When the faces in the Thatcher illusion stimuli (generally called "thatcherized faces") are upside down, the top of the mouth and eyes differs for the two reference frames, but when the thatcherized faces are rightside up, the two reference frames are in agreement, and we get an even uglier Margaret Thatcher.

These first two hypotheses have some empirical support, but they don't fit with all of the data, so researchers have come up with a third hypothesis based on dual process theories of facial perception, which is now well supported empirically4. It begins with the assumption that we process faces by looking at "local features" (e.g., eyes, nose, mouth) and their configuration (how they're organized relative to each other). When the faces are inverted, it is difficult to process the configural information; we just can't seem to process the relationships between the features. So we rely on the local features, which don't appear to be off in the thatcherized faces. However, when the faces are rightside up, both the configural information and the local features are screwy, causing them to look grotesque. Evidence for this hypothesis comes from experiments in which participants are easily able to perceive alterations to local features (e.g., blacking the teeth) when the faces are inverted, but, as the above photos demonstrate, are unable to perceive even large deviations from the normal configuration of those features6.

Interestingly, studies using an electroencephalogram to measure the brain's response to the different photos indicate that our brains do recognize a large difference between the thatcherized and unthatcherized faces, even when they're inverted, despite the fact that participants are rarely consciously aware of the differences7. Since this difference in event-related potentials likely occurs early in the processing of the faces, it may be that higher-order visual processing of the local features overrides the differences that the visual system initially perceives, making it difficult for us to consciously perceive those differences. However, it's not quite clear how this works, and futher neuroscientific research on this aspect of our processing of thatcherized faces may provide interesting insights into face perception.


1Schwaninger, A., Carbon, C.C., & Leder, H. (2003). Expert face processing: Specialization and constraints. In G. Schwarzer & H. Leder (Eds.), Development of Face Processing, pp. 81-97. Göttingen: Hogrefe.
2Thompson, P. (1980). Margaret Thatcher: A new illusion. Perception, 9, 483-484.
3The competing explanations are detailed in Bartlett, J.C., & Searcy, J. (1993). Inversion and configuration of faces. Cognitive Psychology, 25, 281-316.
4Ibid
5Carbon, C.C., Schweinberger, S.R., Kaufmann, J.M>, & Leder, H. (2005). The Thatcher illusion seen by the brain: An event-related brain potentials study. Cognitive Brain Research, 24, 544-555.
6Searcy, J.H., & Bartlett, J.C. (1996). Inversion and processing of component and spatial-relational information of faces. Journal of Experimental Psychology: Human Perception and Performance, 22, 904-915.
7Carbon et al. (2005).

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I wonder if putting the distorted upsidedown photo on the right instead of the left affects the results.

As I was reading in a hurry, I looked quickly at the left upsidedown photo (as I habitually "read" even photos from left to right), assumed with only the barest peripheral glance that the right photo was roughly the same, then read "They look pretty normal, right?" At that point, I went back and actually focused on first the left photo and then the right. It was immediately obvious that the eyes and the mouth had been turned rightside up, but with the mouth still above the eyes. I wonder if maybe some viewers miss the distortions in the right photo partly because they never actually look directly at it.

The smile in the upside down photo looked a bit creepy, but I didn't notice the eyes at all, even though I've seen this kind of thing before.

The first thing I noticed before scrolling down the page was the smiling appearance of the doctored face when upside down, and I wondered if that might influence one's perception, especially since the pleasant aspect is lost when turned right side up.

You know those suspense movies when someone's identity is revealed by removing a mask? Whenever the face is upside down on the screen (usually when the character is sprawled out dead), I'm always asking who is that? is that supposed to be ____? Makes me feel stupid that I can't recognize the face -- even more so because one of my favorite subjects to paint is portraits & I expect myself to be observant. Don't know if this is a related phenomenon or something else, but now I'm curious.

By Rebecca L (not verified) on 24 Sep 2006 #permalink

Recognizing faces when they're upside down is more difficult, yes. That was one of the first signs that face processing is special.

I thought the lady is not for turning.

this is really useless pic ... thw worst pic i ever saw this is not illusion pic

your site is excellent

Amazing and unbelievable

By hemachander (not verified) on 10 Sep 2007 #permalink

.

I had not bothered to analyze my own reaction, but after reading "Julia" September 23, 2006 comment . This is also how I approached and scanned the images. ... so what of folk from non left-right written languages??

.

yes i was able to see the differences in the upside-down picture easily but the grotesque expression only appears in the rightside up picture. very interesting.

soo lame

By stella zinke (not verified) on 14 Oct 2007 #permalink

soo lame

By stella zinke (not verified) on 14 Oct 2007 #permalink

AHAHHAHAHAAHAHAHAHAH c nimporte koi ahahahhahaahaha

this is quite good humour
The main function of this graphic is to excite and stimulate ones mind. its quite ingenius how they used the use of the no arms to portray how hard it would be to be a no armed brick layer. furthermore, they could not ring a qualified contractor because they had no arms and no apposable thumbs to grip a cellular telephonic device. Also the brains cerebrial cortex in conjunction with the sugar serpositories in our brain, the pictures appear to

By Lawrence Mcgillen (not verified) on 29 Oct 2007 #permalink

very good

I hate websites that prevent use of the back button. I curse you.

By C Blackmore (not verified) on 08 Jan 2008 #permalink

That totally freaks me out lol

The top one is the creepyest I think

By Julia Wiener (not verified) on 20 Mar 2008 #permalink

that illusion is so cool

I have never experienced it before. I brought out its printing and made everybody stunned. It proves what an illusion is !

wtf wtf wtf wtf wtf wtf wtf

I THINK THAT THIS IS VERY FABULOUS ILLUTION. VERY INTELLIGENT AND VERY MATHEMATICALLY PLANED. IT NEED A NICE EYE OF OBSETRVATION TO MAKE SUCH AN ART.

c sur kan c trafik� tt sa c plu simple de faire d� illusion

thats really coooool........

By hemla badhe (not verified) on 15 Dec 2008 #permalink

margeret thatcher has scurvy on her balls, so shed deffo get it of me , mr joseph.

download the thatcher image and rotate it 90 degrees. you'll see that the thatcher effect only works on upside-down images. at 90 degrees, both distorted images still look obviously distorted.

i wonder if this is significant?

hi...gud 2 c dis.its fabulous

Casey Serin should be executed.

koooooooooooooooooooooooool

By michael jackson (not verified) on 10 Nov 2009 #permalink

That was rubbish it did absoloutly nothing

i dont like this tis shit!!!!!!!!!!!1 lol this is a silly website fuckin' booooooooo

Doesn't this just sum it all up? That cow cost me my life, my father his, my sister (well maybe not), my mum (ditto). BLOODY LIZZARD!!!!

By Maybe pilot (not verified) on 27 May 2010 #permalink

hi im bitch yaren my sisterr aysun my friend selena gomez the comments That was rubbish it did absoloutly nothing & coooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooool

this was very interestingg

By sweta singh (not verified) on 28 Sep 2010 #permalink

wow! so great... and because of that i didn'tlike it that way...I want it to be something that can make people be amuse of..

mate that is so shit makes a better one ay

By harry long-john (not verified) on 31 Oct 2010 #permalink

hmmm.......something cool......

!!how patithiC!!!!!!!!

By christine (not verified) on 01 Dec 2010 #permalink

its ammazing

balls sacs!

It looks like some short girl from my school that deserves to die!!!! I'm not lying hahahhaha

By Jack the cutie (not verified) on 10 May 2011 #permalink

this is all making fool to the people you bastards..***$$434.......

YOU ARE GOING TO BE A FOOL............................

By Deepak chand (not verified) on 28 May 2011 #permalink

These ones don't really work because the eyebrows are also turned round with the eyes, making it look even weirder.

Now that is a face you do NOT want to see after a bit of 69...