most studies of social mobility, such as the ones described here, have focus upon objective dimensions of mobility–that is to say, how much mobility seems to exist, in which directions and for what parts of the population. Gordon Marshall and David Firth have taken a different approach in their comparative study of social mobility, they have investigated people's subjective feelings about changing class positions. The authors designed their research in response to what they term unsubstantiated speculation among sociologists about the likely effects of social mobility produces a sense of disequilibrium, isolation and unrootedness, others have taken a more optimistic view, suggesting that a gradual process of adaptation to a new class inevitably takes place.