Manipulating the strength of the Ponzo and horizontal-vertical illusions through extraction of local cue information.

Previous research has shown that by placing nontargets around the endpoints of the shaft of the Mueller-Lyer illusion it is possible to markedly affect its normal strength. Using the same technique with the Ponzo illusion and the horizontal-vertical illusion, the current study demonstrated a similar ability to affect these other illusions of length. These findings provide varying amounts of support or challenges for different theories of illusion formation.

Hand preference and skilled hand performance among individuals with successful rightward conversions of the writing hand.

Searleman and Porac (2001) studied lateral preference patterns among successfully switched left-hand writers, left-hand writers with no switch pressure history, and left-hand writers who did not switch when pressured. They concluded that left-handers who successfully shift to right-hand writing are following an inherent right-sided lateralisation pattern that they already possess. Searleman and Porac suggested that the neural mechanisms that control lateralisation in the successfully switched individuals are systematically different from those of other groups of left-handers.

Patterns of handedness and footedness in switched and nonswitched Brazilian left-handers: cultural effects on the development of lateral preferences.

In Western societies most left-handers who are pressured to write with the right hand resist the pressure. Searleman and Porac (2001, 2003) studied North American participants and proposed that mixed left-handers, more so than consistent left-handers, would be likely to successfully acquire right-handed writing skills on a long-term basis. In accordance with their two-phenotype hypothesis, the majority of switched left-handers (SLH) in their studies exhibited right-sided asymmetries on other handedness tasks such as throwing, and, in addition, tended to be right-footed.

A cross-cultural comparison of pressures to switch left-hand writing: Brazil versus Canada.

Attempts to switch left-hand preferences towards the right side are socialisation practices found in many countries (Perelle & Ehrman, 1994). Although researchers acknowledge that pressures against left-hand use contribute to the cross-cultural fluctuations in the prevalence of left- versus right-hand preference, there has been little systematic cross-cultural study of how these pressures are applied, and who are the major agents applying the pressures to change. Our study explored specific rightward conversion practices and the results of these practices among individuals from two countries.

The relationship between hand preference consistency, health, and accidents in a sample of adults over the age of 65 years.

As a result of the Coren and Halpern (1991) hypothesis that left hand preference may be associated with decreased survival fitness, there has been interest in exploring the relationship between hand preference and indices of health status. In a series of studies of university-aged adults, Hicks and his colleagues found a higher prevalence of accidental injuries, falls, and sleep problems among individuals with mixed, rather than left, hand preference. They argued that hand preference consistency, not side, may be a marker for possible reduction in health and well-being.