>> less reliable/continuous/predictable access to material things, meaning they would rationally seize immediate opportunities rather than taking the risk of a

>> less reliable/continuous/predictable access to material things, meaning they would rationally seize immediate opportunities rather than taking the risk of a larger future opportunity THIS — the environment definitely changes what is the most rational behavior. In economics, this is Counterparty Risk — the risk that the other party will fail to fulfill their obligation. E.g., as a vendor it is rational to accept a piece of plastic from a complete stranger without a word, because the issuer of the card is good for the money, and has taken on the problem if the buyer doesn't pay their bill that month. For kids in affluent stable households, it is rational to expect that they'll get the second cookie in 20 minutes. For a kid in an unstable household, being told by someone who neither looks nor talks like they do, that they'll get two cookies in 20 minutes, it's often rational to take what you can get NOW. The marshmallow test measures mainly environmental counterparty risk in everyday events. Seems when controlling for those factors, the 'marshmallow effect' disappears. This is good science. Discover an effect. Generate a hypothesis. Keep testing until you find the limits of that hypothesis, and/or hidden variables.