Poor People Cannot Think Clearly?

Senator Miriam Defensor Santiago said, "Only taxpayers should be allowed to vote", and science might just be on her side. The senator from the Philippines made this statement during a press briefing on September 4, 2013. In the statement, the senator equates nonpayment of taxes to extreme poverty. In this dire situation, a poor person is extremely vulnerable to patronage politics. Votes or support can easily be bought even with token amounts. As a result, "taxpayers are being ruled by the choice of the nontaxpayers". Science may be supporting Senator Santiago's proposal to not allow poor people to vote.
Senator Miriam Defensor Santiago
Above photo copied from http://en.wikipedia.org/wiki/Miriam_Santiago
In the August 30, 2013 issue of the journal Science, an article on the relationship between poverty and thinking was published. The article, "Poverty Impedes Cognitive Function", authored by researchers from Harvard and Princeton, has the following abstract:
The poor often behave in less capable ways, which can further perpetuate poverty. We hypothesize that poverty directly impedes cognitive function and present two studies that test this hypothesis. First, we experimentally induced thoughts about finances and found that this reduces cognitive performance among poor but not in well-off participants. Second, we examined the cognitive function of farmers over the planting cycle. We found that the same farmer shows diminished cognitive performance before harvest, when poor, as compared with after harvest, when rich. This cannot be explained by differences in time available, nutrition, or work effort. Nor can it be explained with stress: Although farmers do show more stress before harvest, that does not account for diminished cognitive performance. Instead, it appears that poverty itself reduces cognitive capacity. We suggest that this is because poverty-related concerns consume mental resources, leaving less for other tasks. These data provide a previously unexamined perspective and help explain a spectrum of behaviors among the poor. We discuss some implications for poverty policy.
Although the science may seem in agreement with the senator's view, that is, the poor has difficulty making the right choice or decision, the paper does NOT make the same recommendation of taking away the right to vote from the poor. Instead, the researchers maintain that policies that recognize and appropriately respond to this condition must be drawn. The last thing a poor person needs is to be further marginalized by society.

The study demonstrates in two different experiments how significantly financial worries can impair the cognitive ability of individuals. The first experiment involves shoppers in New Jersey. Participants are introduced to various scenarios that typify a financial problem. Some are shown difficult situations. A costly automobile repair ($1500) could be one example. These are called "Hard" scenarios while others are shown much easier situations. A cheaper repair ($150) is an example. These scenarios aim to trigger the participant's own financial concerns. The participants then take two exams that measure cognitive function. In one experiment, getting the correct answer even comes with a financial reward. Yet, even with incentives, those who are financially worried do not perform well:

Accuracy on the Raven’s matrices and the cognitive control tasks in the hard and easy conditions, for the poor and the rich participants, when incentives were provided.
Mani et al., Science 341 (6149): 976-980
The differences seen above disappear when the participants are provided scenarios that are not financially related. In the second experiment, sugarcane farmers in Tamil Nadu, India perform much better in cognitive exams when the exams are administered at post-harvest.

The authors write in their discussion of the findings:
The data reported here suggest a different perspective on poverty: Being poor means coping not just with a shortfall of money, but also with a concurrent shortfall of cognitive resources. The poor, in this view, are less capable not because of inherent traits, but because the very context of poverty imposes load and impedes cognitive capacity. The findings, in other words, are not about poor people, but about any people who find themselves poor. 
How large are these effects? Sleep researchers have examined the cognitive impact (on Raven’s) of losing a full night of sleep through experimental manipulations (38). In standard deviation terms, the laboratory study findings are of the same size, and the field findings are three quarters that size. Put simply, evoking financial concerns has a cognitive impact comparable with losing a full night of sleep.
Being poor and therefore financially worried is equivalent to losing a full night of sleep.

On basic education, this study has serious implications. Child labor alone demonstrates that a student may not have all the cognitive resources a normal child has. Poor children likewise are exposed to financial worries when schools impose projects that children can not afford. Selling raffle tickets for fundraising, parties requiring new clothes, learning materials that need to be paid - These can easily become formidable financial concerns for a student. These worries capture the attention of a child leaving less room for learning.

The appropriate solution is one that addresses the situation correctly and responsibly. It is wrong to deny schooling to children who are already working. It is wrong to tell students not to attend school anymore if they have financial worries. Similarly, not allowing the poor to vote is likewise an inappropriate response. Perhaps, the good senator from the Philippines is also not thinking clearly given the attention and frustration over massive corruption the country currently faces.