Tetrachromacy

A woman with tetrachromacy

Newcastle University neuroscientist Dr. Gabriele Jordan, recently announced that she has identified a woman who is a "tetrachromat," that is, a woman with the ability to see much greater color depth than the ordinary person.

According to Daily Mail, an ordinary person can perceive a million different hues of colors. The power to distinguish the hues comes from cells in our eyes called cones. In the average person, there are three types of cones each of which is triggered by different wavelengths of light.

Discover Magazine explains that most people have three types of cones, and are said to be "trichromats." Color blind individuals have only two types of cones and they are said to be "dichromats." Almost all animals, including dogs and New World Monkeys are dichromats.

However, scientists have long believed that there are people with four cones who can see a wider range of colors than most of us can detect. These persons are called "tetrachromats," and can see a hundred million colors. From the perspective of such people, the hues familiar to trichromats fracture further into more subtle shades of differences that have not been given names since most of us are trichromats who cannot see these shades and name them.

Jordan and her colleagues have for 20 years searched for people endowed with super color vision, or tetrachromatic vision. According to Discover Magazine, Jordan found a tetrachromat two year ago. Although the person is the first tetrachromat known to science, the researchers believe there are others.

Discover Magazine reports that Jordan and her team found many people with four types of cones but only one person passed the tests for tetrachromatic vision. The woman, identified as subject cDa29, is a doctor living in northern England. Jordan and her colleagues believe there may be other persons with tetrachromatic vision.

Jordan told Discover Magazine that she was very excited by her discovery. It took 20 years to search for her to identify the first true tetrachromat. But a question immediately arose: Why is it that there are people with four cones who apparently do not exhibit tetrachromatic vision?

See more in: http://digitaljournal.com/article/326976

 

 

 

Absolute pitch

People with absolute pitch can reproduce notes that have once been heard without any help.  T
They can name a note when heard. It is mostly influenced by cultural exposure to music. Absolute pitch is much more common in people who, as born language, speak  "tonal" languages, like Chinese or Vietnamese. It has been suggested that most infants acquiren this ability when they learn to speak tonal languages.

An absolute listener's sense of hearing is typically no keener than that of a non-absolute ("normal") listener. 

Left and right hemisphere of a person with absolute pitch

The prevalence of absolute pitch is higher among those who are blind from birth as a result of optic nerve hypoplasia.

Absolute pitch is considerably more common among those whose early childhood was spent in East Asia. This might seem to be a genetic difference; but people of East Asian ancestry who are reared in North America are significantly less likely to develop absolute pitch than those raised in East Asia,so the difference is more probably explained by experience. The language that is spoken may be an important factor; many East Asians speak tonal languages such as Mandarin and Cantonese, while others (such as those in Japan and certain provinces of Korea) speak pitch-accent languages, and the prevalence of absolute pitch may be partly explained by exposure to pitches together with meaningful musical labels very early in life.

Absolute pitch ability has higher prevalence among those with Williams Syndrome and those with an autism spectrum disorder, with rates as high as 30% claimed, stating that the rate among musicians in general is far lower.