All these biological biases have been the subject of much research over the years. Which does not mean they are true, of course.....

• We find it emotionally easier to accept a proposal than reject it. That's why we tend to believe the media and salesmen. Even of snake oil.
• We find it easier to follow the crowd.
• Discussions within closed groups (such as the regular lunch group at the office) can be self-reinforcing. They can lead to agreement on propositions that are likely to be false.
• When viewing two independent events, we tend to assume causality. The Aztecs required human sacrifice to prevent the sky from falling on the earth. Hey, it had worked so far!
• We have probability blindness. We are 90% likely to go on holiday and 10% likely to cancel through family illness. We cannot imagine the composite event which is 90% of one and 10% of the other.
• We tend to ignore the small probability of large losses. In real life this is a virtue - otherwise we would never go outside for fear of death by lightning. In investment, the consequence may be precipice bonds.
• We give too much weight to recent evidence and not enough to the distant past.
• We easily confuse conditional and unconditional probabilities. See the Sally Clark and other cot-death cases. (The chance of Sally Clark having two children die natural cot-deaths was quoted by an 'expert' as 73 million to 1. This was wrong because: a) one cot-death indicates a pre-dispostion towards that condition, so the probability of the second death goes up: odds come down to maybe a million to one; b) the correct odds for prosecution are not the odds of specifically Sally Clark having two cot-deaths but the odds of this happening to anyone in the UK. Put another way: every year one mother in the UK suffers a second cot death, by the terrible laws of chance. Are they therefore to be prosecuted for double murder?)
• We are more likely to take risks to reverse a loss than to increase a profit. This is illogical - losses should make us less able to risk further losses.
• We don't like to face disappointment. That is why people like stop-losses. A better name would be 'hide-losses'.

Investment products may be structured to exploit these weaknesses.