The Daily Omnivore

The Semmelweis reflex is a metaphor for the reflex-like tendency to reject new evidence or new knowledge because it contradicts established norms, beliefs or paradigms.

The term originated from Ignaz Semmelweis, who discovered that childbed fever mortality rates could be reduced ten-fold if doctors would wash their hands (we would now say disinfect) with a chlorine solution between having contact with infected patients and non-infected patients. His hand-washing suggestions were rejected by his contemporaries.

A hot-cold empathy gap is a cognitive bias in which a person underestimates the influences of visceral drives, and instead attributes behavior primarily to other, nonvisceral factors. The term was coined by psychologist and behavioral economist George Loewenstein. He argued that human understanding is ‘state dependent.’ For example, when one is angry, it is difficult to understand what it is like for one to be happy, and vice versa; when one is blindly in love with someone, it is difficult to understand what it is like for one not to be. The implications of this were explored in the realm of sexual decision-making, where young men in an unaroused ‘cold state’ fail to predict that when they are in an aroused ‘hot state’ they will be more likely to make risky sexual decisions, such as not using a condom.

The empathy gap has also been an important idea in research about the causes of bullying. In one study examining a central theory that, ‘only by identifying with a victim’s social suffering can one understand its devastating effects,’ researchers created five experiments. The first four examined the degree to which participants in a game who were not excluded could estimate the social pain of those participants who were excluded. The findings were that those were not socially excluded consistently underestimated the pain felt by those who were excluded.

The illusion of transparency is a tendency for people to overestimate the degree to which their personal mental state is known by others. Another manifestation of the illusion is a tendency for people to overestimate how well they understand others’ personal mental states. This cognitive bias is similar to the illusion of asymmetric insight.

Psychologist Elizabeth Newton created a simple test that she regarded as an illustration of the phenomenon. She would tap out a well-known song, such as ‘Happy Birthday’ or the national anthem, with her finger and have the test subject guess the song. People usually estimate that the song will be guessed correctly in about 50 percent of the tests, but only 3 percent pick the correct song. The tapper can hear every note and the lyrics in his or her head; however, the observer, with no access to what the tapper is thinking, only hears a rhythmic tapping.

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The Thatcher effect is a phenomenon characterized by difficulty detecting local feature changes in an upside down face, despite identical changes being obvious in an upright face. It is named after British former Prime Minister Margaret Thatcher on whose photograph the effect has been most famously demonstrated by Peter Thompson of the University of York (UK) in 1980. The effect is thought to be due to psychological processes involved in face perception which are tuned especially to upright faces. Faces seem unique despite the fact that they are very similar. It has been hypothesized that we develop processes to differentiate between faces that rely as much on the configuration (the structural relationship between individual features on the face) as the details of individual face features, such as the eyes, nose and mouth. When a face is upside down, the configural processing cannot take place, and so minor differences are more difficult to detect.

This effect is not present in people who have some forms of prosopagnosia, a disorder where face processing is impaired, usually acquired after brain injury or illness. This suggests that their specific brain injury may damage the process that analyses facial structures. Rhesus monkeys also show the Thatcher effect, raising the possibility that some brain mechanisms involved in processing faces may have evolved in a common ancestor 30+ million years ago. The basic principles of the Thatcher Effect in face perception have also been applied to biological motion. The local inversion of individual dots is hard, and in some cases, nearly impossible to recognize when the entire figure is inverted.