Analysis and interpretation of serial position data

Abstract

The representation of serial position in sequences is an important topic in a variety of cognitive areas including the domains of language, memory and motor control. In the neuropsychological literature, serial position data have often been normalised across different lengths, and an improved procedure for this has recently been reported by Mactynger and Shallice (2009).Effects of length and a U-shaped normalised serial position curve have been criteria for identifying working memory deficits. We present simulations and analyses to illustrate some of the issues that arise when relating serial position data to specific theories. We show that critical distinctions are often difficult to make based on normalised data. We suggest that curves for different lengths are best presented in their raw form, and that binomial regression can be used to answer specific questions about the effects of length, position and linear or non-linear shape that are critical to making theoretical distinctions.Serial position data 3

Repeated attempts, phonetic errors, and syllabifications in a case study:Evidence of impaired transfer from phonology to articulatory planning

“…middle or at the end of words are produced less accurately than at the beginning. Middle phonemes are more susceptible to interference from flanking phonemes (a U-shaped serial position curve) and non-initial phonemes have more chance to decay while the beginning of the word is being produced (a linearly decreasing curve; Glasspool et al, 2006;Olson et al, 2010;Romani et al, 2011b;Ward & Romani, 1998).…”

“…Considering the rate of errors per phoneme and effects of word position is more informative. A buffer impairment predicts that error rates per phoneme will increase at all positions in longer words because all phonemes will deteriorate faster/be more susceptible to interference when more of them need to be stored (a disproportionate length effect, see Olson et al, 2010;Romani et al, 2011b). A buffer impairment may also predict linear positional effects since phonemes at the end of the word may have more chance to decay (Glasspool et al, 2006;Schiller et al, 2001;Ward & Romani, 1998).…”

“…If there are only effects of position, lines should decrease with position, but lines for longer and shorter words should overlap. Finally, if there are both effects of position and length, lines should angle downward with position, but lines for longer words should also be offset (see Olson et al, 2010). Results were analysed using binomial regression with phonemes preserved/not preserved as the dependent variable and word length and position as the independent variables.…”

Why do we mipsell the middle of words? Orthographic texture and the serial position effect.

“…Spelling accuracy has been demonstrated to vary as a function both of letter position within the syllable (Caramazza & Miceli, 1990) and morphemic status (Badecker, Hillis, & Caramazza, 1990); it is possible that SLC also varies as a function of these variables. Furthermore, Olson, Romani, and Caramazza (2010) suggested that measures of spelling accuracy as a function of letter position not be collapsed across word length for a single five-letter word accuracy function; instead, serial position effects should be investigated separately for different word lengths. However, because most studies reporting serial position effects include multisyllabic and -morphemic words and collapse across word length, Study 1b was conducted with a second, independently selected sample of 300 words that varied in word length and number of syllables and morphemes.…”

“…Spelling accuracy has been demonstrated to vary as a function both of letter position within the syllable (Caramazza & Miceli, 1990) and morphemic status (Badecker, Hillis, & Caramazza, 1990); it is possible that SLC also varies as a function of these variables. Furthermore, Olson, Romani, and Caramazza (2010) suggested that measures of spelling accuracy as a function of letter position not be collapsed across word length for a single five-letter word This document is copyrighted by the American Psychological Association or one of its allied publishers.…”