Mixing Memory

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:


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


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):


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.
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).


  1. #1 Julia
    September 23, 2006

    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.

  2. #2 rehana
    September 23, 2006

    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.

  3. #3 Rebecca L
    September 24, 2006

    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.

  4. #4 Chris
    September 24, 2006

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

  5. #5 Harry
    August 2, 2007

    I had no idea what this illusion was called before!

  6. #6 MartinC
    August 3, 2007

    I thought the lady is not for turning.

  7. #7 know
    August 28, 2007

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

  8. #8 alauddin
    September 1, 2007

    your site is excellent

  9. #9 hemachander
    September 11, 2007

    Amazing and unbelievable

  10. #10 good luck
    September 22, 2007


  11. #11 Monado
    September 23, 2007

    I noticed that the eyes were upside down but not the mouth.

  12. #12 ewailMe
    September 28, 2007


    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??


  13. #13 afan
    October 4, 2007

    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.

  14. #14 stella zinke
    October 15, 2007

    soo lame

  15. #15 stella zinke
    October 15, 2007

    soo lame

  16. #16 georgioo
    October 24, 2007

    AHAHHAHAHAAHAHAHAHAH c nimporte koi ahahahhahaahaha

  17. #17 jonh
    October 28, 2007

    well it is a nice illusion but not a very complicated one.


  18. #18 Lawrence Mcgillen
    October 30, 2007

    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

  19. #19 izzy
    November 9, 2007

    that was really cool(not)

  20. #20 shabu
    November 24, 2007

    very good

  21. #21 ally2
    December 22, 2007


  22. #22 C Blackmore
    January 8, 2008

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

  23. #23 sizGaysiniz
    February 14, 2008

    A.q mmilletimi sikyosunuz o笡rı

  24. #24 Julia Wiener
    March 20, 2008

    That totally freaks me out lol

    The top one is the creepyest I think

  25. #25 geskif
    March 25, 2008

    that illusion is so cool

  26. #26 mehgan
    April 3, 2008

    this is gayyy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!11

  27. #27 peter
    May 15, 2008

    Everybody on this website is gay

  28. #28 peter
    May 15, 2008


  29. #29 north
    June 4, 2008


  30. #30 subrata
    July 20, 2008

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

  31. #31 haley
    July 29, 2008

    wtf wtf wtf wtf wtf wtf wtf

  32. #32 nivedha
    August 20, 2008


  33. #33 romaain
    September 2, 2008

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

  34. #34 shekhar
    October 31, 2008

    thats really something dude………
    need to observed closely to notice that…..

  35. #35 mark john
    December 3, 2008

    it so fun

  36. #36 hemla badhe
    December 16, 2008

    thats really coooool……..

  37. #37 John Cena
    January 5, 2009


  38. #38 joseph
    January 9, 2009

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

  39. #39 Rohith Singh
    June 1, 2009

    Nice illusions but not great to watch….
    For really gr8 illusions
    visit : http://images-world.blogspot.com/

  40. #40 karla
    June 3, 2009


  41. #41 The Science Pundit
    June 25, 2009

    It seems that monkeys react the same way we do to Thatcherized faces. So the way we recognize faces may be quite ancient indeed.

  42. #42 sam
    June 27, 2009

    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?

  43. #43 theresa
    July 13, 2009

    its so simple
    i can do it!!!!!!

  44. #44 sheenu
    August 31, 2009

    hi…gud 2 c dis.its fabulous

  45. #45 harsh
    October 6, 2009

    well boy

  46. #46 frog
    October 20, 2009

    Casey Serin should be executed.

  47. #47 michael jackson
    November 11, 2009


  48. #48 WH546
    December 22, 2009

    That was rubbish it did absoloutly nothing

  49. #49 Sam
    January 3, 2010

    This is so confusing and freaky!!

  50. #50 AmyLeech
    February 5, 2010

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

  51. #51 Maybe pilot
    May 27, 2010

    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!!!!

  52. #52 yaren güngör
    June 3, 2010

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

  53. #53 sweta singh
    September 28, 2010

    this was very interestingg

  54. #54 chariy
    October 18, 2010

    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..

  55. #55 harry long-john
    October 31, 2010

    mate that is so shit makes a better one ay

  56. #56 shailaja
    November 20, 2010

    hmmm…….something cool……

  57. #57 christine
    December 2, 2010

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

  58. #58 romes
    December 10, 2010

    its ammazing

  59. #59 krishna
    March 3, 2011

    balls sacs!

  60. #60 Jack the cutie
    May 10, 2011

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

  61. #61 shikhar
    May 25, 2011

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

  62. #62 Deepak chand
    May 28, 2011

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

  63. #63 keith wicks
    November 14, 2011
  64. #64 keith wicks
    November 14, 2011

    thatchers role in BAE / Saudi deal, http://www.gopetition.com/petition/41746.html

  65. #65 keith wicks
    November 14, 2011
  66. #66 Seb
    December 30, 2011

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

  67. #67 Petrie
    January 21, 2012

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

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