First year practicals

1. First year practicals Lab 4: Pseudo-homophonesThey sound like words, but they aren’t

2. Objectives of this class • In this class you will; • learn about pseudohomophones • learn to generate your own study in PsychoPy

3. Pseudohomophones • When people are asked to decide if a letter string is a word their responses to negative stimuli are slower when the letter string sounds like a real word • Time to respond ‘no’ is greater for ‘bild’ than for ‘jate’ • Rubenstein, Lewis & Reubenstein (1971) • The pseudohomophone effect is evidence that visually presented words are phonologically encoded. • This process of phonological encoding occurs before searching the lexicon. • Orthographic checks are made after a phonological match is found

4. The disappearing pseudohomophone effect • Martin (1982) pointed out that the two kinds of non-words used by Rubenstein et al (1971) don’t just differ phonologically • ‘bild’ sounds like a word and looks like a word • ‘jinf’doesn’t sound like a word and doesn’t look like a word • Are people really using phonological information or are they really using orthographic information? • Martin showed that if the non-homophonic control words looked as much like a word as the pseudohomophones, the pseudohomophone effect disappeared

5. The pseudohomophonic effect is back again. • Underwood et al (1998) “When readers encountered homophones during a training phase of the experiment, then a pseudohomophone effect was observed in a later block of trials which contained no homophones. A second group of readers encountered no homophones during either phase of the experiment and they did not show a pseudohomophone effect.” (Canadian Journal of Psychology, 1988, 42, pg 24). • People did use phonological evidence when it was necessary and did not use it when it was not needed

6. The experimental task • The usual procedure is: • show oneletter string for up to 2s • ask the participant to decide whether it is a word • this is known as the lexical decision task (LDT) • An alternative procedure is the Forced Choice Reaction Time task: • show two letter strings for up to 2s (a word & a non-word string) • ask participants to decide which letter string is a word

7. Adapting Underwood et al’s procedure • Underwood et al’s (1988) design • A training phase on the lexical decision task • One group of participants trained with homophones • One group of participants trained without homophones • A test phase on the lexical decision task • The FCRT adaptation • A training phase on the FCRT task • One group of participants trained with homophones • One group of participants trained without homophones • A test phase on the FCRT task

8. Experimental Design • The independent variable – Type of Training • With homophones • Without homophones • The dependent variable • Difference in time to respond to control strings and to respond to pseudohomophones • Unit of measurement • seconds

9. Theoretical Predictions • According to Underwood et al (1988) the pseudohomophone effect is found when participants are trained on homophones. • Training includes homophones • RT for pseudohomophones > RT for control strings • Training does not include homophones • RT for pseudohomophones = RT for control strings • Therefore in this experiment • (RT for pseudohomophones - RT for control strings) for homophone training > (RT for pseudohomophones - RT for control strings) for no homophone training

10. References in Brief • Rubenstein et al (1971). Journal of Verbal Learning and Verbal Behaviour, Vol 10, starting page: 57 • Coltheart et al (1977). Attention and Performance, Volume 6, starting page: 535 • Martin (1982) Quarterly Journal of Experimental Psychology, Section A – Human experimental Psychology, Vol 34, starting page: 395 • Underwood (1988) Canadian Journal of Psychology – Revue Canadienne de Psychologie, Vol 42, starting page: 24.