A criticism of Romanian orphan research is that deprivation is only one factor in development, there may have been other confounding variables. The orphans' experienced very little or no mental stimulation and were often malnourished. This suggests that there are multiple risk factors involved in establishing the effects of institutional care. Therefore, it is difficult to interpret the results of studies as the sole effect of deprivation as there are many different influences that affected these children, such as living in poverty.