It is a common, yet embarrassing scenario but British scientists have now offered an insight into why we forget people’s names only for them to return hours later.

Memory formation is an energy-consuming process. The brain would need to decide if it was worth expending energy for the consolidation of that particular memory

Scientists have observed that in all animals, memories that can be recalled several hours after learning them may become inaccessible for brief periods after their formation.

Although it is not fully understood why such lapses happen, it is believed to be because they are a necessary part of the brain’s process to consolidate memories.

University of Sussex neuroscientists have now discovered that causing a disturbance during these memory lapses disrupts the process and appears to prevent the memories being formed.

One of the experts involved in the study, Ildiko Kemenes, said: “Scientists have long wondered why the brain shows these memory lapses.

“Here we showed that lapses in memory coincide with periods when consolidation of memory is susceptible to disturbances from outside the memory network.

“Changes in the molecular pathways underlying consolidation are responsible for these periods of vulnerability.”

Kemenes and colleagues introduced snails to an unfamiliar substance during feeding so that the animals would learn to recognise it as food.

When they were fed later, scientists found the snails responded to the stimulus, with memory lapses after 30 minutes and two hours, before the memory became consolidated at about four hours.

But if the snail received another different stimulus during the memory-lapse periods, the memory consolidation became disrupted, it was discovered.

Kemenes said: “Memory formation is an energy-consuming process. The brain would need to decide if it was worth expending energy for the consolidation of that particular memory.

“The brain has a restricted capacity to learn things and preventing some memory formation would be a way to avoid overload.”

The next stage of the study, which is funded by the Biotechnology and Biological Sciences Research Council (BBSRC), will investigate what happens to the brain during the memory disruption.