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INTRODUCTION
The Pyramids and Palm Trees Test (PPT) was developed by Howard and Patterson (1992) to measure the capacity to access detailed semantic information about words and objects. In the PPT, subjects are shown a simple drawing or an oral word to be semantically matched to one or two probe drawings or words. This test was validated and normalized with a group of 60 healthy English-speaking subjects in which no subject made more than three errors on the test. Howard and Patterson (1992) consider as clinically significant more than five incorrect answers, although a rationale for this cut-point was not explained.
Neuropsychological tests such as category fluency and confrontation naming and vocabulary tests, are traditionally used to assess semantic memory. These tasks are influenced by sociodemographic factors, such as age, gender, and education level. Research has shown age-related decreases on semantic memory tasks that assess word comprehension abilities and general knowledge (Nyberg et al., 2003), confrontation naming (Randolph et al., 1999) and fluency (Nyberg et al., 2003), which have been attributed to retrieval failures with preserved representations in semantic memory (Nyberg et al., 2003). Gender effects are category specific. Healthy females perform better than males in naming fruits (Capitani et al., 1999) and living categories (Laws, 1999), whereas males perform better in naming tools (Capitani et al., 1999), and non-living categories (Laws, 1999). This category specific gender difference has been explained by a familiarity effect (Albanese et al., 2000). Number of years of education affects picture naming tasks (Randolph et al., 1999) and semantic fluency tests (Da Silva et al., 2004). Individuals with more years of education perform better on these tasks probably because of a richer pool of semantic information in comparison to lesser-educated individuals (Da Silva et al., 2004).
We have found no other normative data on PPT test performance except for those of Howard and Patterson (1992). The current study was designed to examine the effect of sociodemographic factors on the PPT in Spanish speakers, because this has never been done and these factors influence other semantic memory tasks, as noted earlier. These results will also provide preliminary normative data on the PPT for a Spanish-speaking population.
METHOD
Participants
A total of 260 healthy participants were recruited. All eligible subjects belonged to...