That the poor eat more junk food overall than the more affluent is quite well-established, but the reasons for this are not clear.[31] Few studies have focused on variations in food perception according to socio-economic status (SES); some studies that have differentiated based on SES suggest that the economically challenged don't perceive healthy food much differently than any other segment of the population.[32] Recent research into scarcity, combining behavioral science and economics, suggests that, faced with extreme economic uncertainty, where even the next meal may not be a sure thing, judgment is impaired and the drive is to the instant gratification of junk food, rather than to making the necessary investment in the longer-term benefits of a healthier diet.[33][34]