According to the Pollyanna Principle, the brain processes information that is pleasing and agreeable in a more precise and exact manner as compared to unpleasant information.  The term can be used to refer to a variety of human tendencies: faster recognition of pleasant stimuli, the perception of pleasant stimuli occurring more regularly, the tendency for an individual to expose themselves to pleasant stimuli more frequently than unpleasant stimuli, the increasing accuracy of recall for pleasant stimuli, the manner in which positive information is processed more rapidly, etc. (Matlin & Gawron, 1979).  The explanation behind this phenomenon is that the cognitive processes, which give rise to language and behavior, favor the pleasant/positive information over unpleasant/negative information (Matlin & Stang, 1978). The Pollyanna Principle is a pervasive fact of human personalities: people want to hear no evil, see no evil, speak no evil, believe no evil.

The rose-colored glasses that come with the Pollyanna Principle will get us into trouble as forecasters, for it will leave us with unrealistic optimistic guesses about the future, in which hope and expectation are muddled.  Examples are abundant:

1. Coral reefs in the Pacific and Indian oceans are disappearing faster than had previously been thought, a scientific study has shown.
2. Models Underestimate Loss of arctic sea ice

When predicting future natural events, there is no room for wishful thinking.

For further reading:

Matlin, Margaret W.,  and Stang, David J. (1978). The Pollyanna Principle: Selectivity in Language, Memory, and Thought. Schenkman, ISBN 978-0-87073-815-9