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WonderBrain fact

Dopamine, a chemical messenger in the brain, is central to motivation and learning. Its activity changes most when things turn out better or worse than expected, which helps the brain learn which cues are worth paying attention to.

Neuroscience

MindScience

The story behind the card

The key experiments were made in the 1980s and 1990s by the neuroscientist Wolfram Schultz, then at the University of Fribourg in Switzerland, who recorded dopamine cells in monkeys. When a drop of juice arrived unexpectedly, the cells became active. Once a light or a sound reliably came before the juice, they responded to the signal instead and barely reacted to the juice itself. If the expected juice did not arrive, their activity dropped below normal. The cells were tracking the gap between what was expected and what happened, now called the reward prediction error, and some computer learning methods use a similar signal. This is how a phone's ping can become a cue that grabs attention: it hints that something interesting may be waiting. That is different from saying every notification gives everyone the same burst of pleasure.

Türkçe oku
Dopamin, beyindeki kimyasal habercilerden biridir ve motivasyonla öğrenmede merkezî bir rol oynar. Etkinliği en çok, bir şey beklenenden iyi ya da kötü sonuçlandığında değişir; bu da beynin hangi işaretlerin dikkate değer olduğunu öğrenmesini sağlar.

Bu konudaki belirleyici deneyleri 1980'ler ve 1990'larda nörobilimci Wolfram Schultz yaptı; Schultz o yıllarda İsviçre'deki Fribourg Üniversitesi'ndeydi. Maymunların beynindeki dopamin hücrelerinin etkinliğini kaydetti. Hayvana beklenmedik bir anda bir damla meyve suyu verildiğinde bu hücreler hemen etkinleşiyordu. Bir ışık ya da ses meyve suyunun geleceğini düzenli olarak haber vermeye başlayınca, hücreler artık bu işarete tepki veriyor, meyve suyunun kendisine neredeyse hiç tepki vermiyordu. Beklenen meyve suyu gelmediğinde ise etkinlikleri normalin altına düşüyordu. Yani hücreler, beklenenle gerçekleşen arasındaki farkı izliyordu. Bu farka bugün “ödül tahmin hatası” deniyor; bazı makine öğrenmesi yöntemleri de benzer bir sinyal kullanır. Telefon bildiriminin dikkatimizi bu kadar çekmesi de bununla ilgilidir: Bildirim sesi, ilginç bir şeyin gelmiş olabileceğini haber veren bir işarete dönüşür. Ama bu, her bildirimin herkese aynı ölçüde haz verdiği anlamına gelmez.

Sources and further reading

Background reading: Dopamine
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