Nevertheless, Buddhists do not all follow them with the same strictness. Devotees who have just started keeping the precepts will typically have to exercise considerable restraint. When they become used to the precepts, they start to embody them more naturally. Researchers doing field studies in traditional Buddhist societies have found that the five precepts are generally considered demanding and challenging. For example, anthropologist Stanley Tambiah found in his field studies that strict observance of the precepts had "little positive interest for the villager ... not because he devalues them but because they are not normally open to him". Observing precepts was seen to be mostly the role of a monk or an elderly lay person. More recently, in a 1997 survey in Thailand, only 13.8% of the respondents indicated they adhered to the five precepts in their daily lives, with the fourth and fifth precept least likely to be adhered to. Yet, people do consider the precepts worth striving for, and do uphold them out of fear of bad karma and being reborn in hell, or because they believe in that the Buddha issued these rules, and that they therefore should be maintained. Anthropologist Melford Spiro found that Burmese Buddhists mostly upheld the precepts to avoid bad karma, as opposed to expecting to gain good karma. Scholar of religion Winston King observed from his field studies that the moral principles of Burmese Buddhists were based on personal self-developmental motives rather than other-regarding motives. Scholar of religion Richard Jones concludes that the moral motives of Buddhists in adhering to the precepts are based on the idea that renouncing self-service, ironically, serves oneself.