SummaryAn experimental psychological study was undertaken to assess the effect of a change in dietary habit upon behavioural development, using as a laboratory animal male Wistar rats maintained on natural foods and a processed food. Forty male Wistar rats were weaned at 21 days of age and divided into two equal groups. Group 1 was fed natural food (pressed wheat, dried fish, peanuts, cabbage and soybeans) and group 2 was fed powdered food. At 68 days of age, the rats were tested in a T‐maze. The results showed that Group 1 excelled with regard to T‐maze learn