Telescoping effect

In cognitive psychology, the telescoping effect (or telescoping bias) is a phenomenon in which people underestimate the recency of recent events (backward telescoping), and overestimate the recency of distant events (forward telescoping).

The approximate time at which events switch from backward to forward telescoping is three years, with events occurring three years in the past being equally likely to be reported with forward telescoping bias as with backward telescoping bias. Although telescoping occurs in both the forward and backward directions, in general the effect is to increase the number of events reported too recently. This net effect in the forward direction is because forces that impair memory, such as lack of salience, also impair time perception.

Telescoping leads to an over-reporting of the frequency of events. This over-reporting is because participants include events beyond the period, either events that are too recent for the target time period (backward telescoping) or events that are too old for the target time period (forward telescoping).