JCPSLP VOL 15 No 1 March 2013

Acknowledgments Thank you to all of the participants in the study and their families. I additionally thank Jessica Barlow for all of her guidance, mentoring, and support, as well as Sonja Pruitt, Eric Bakovi ´c, Rachel Mayberry, and Vic Ferreira for their comments on earlier aspects of this work. This research was supported in part by a National Institute on Deafness and Other Communication Disorders training grant, an American Speech-Language-Hearing Foundation New Century Scholars Program Doctoral Scholarship, and the Sheila and Jeffrey Lipinsky Family Doctoral Scholarship. References Andrews, N., & Fey, M. (1986). Analysis of the speech of phonologically impaired children in two sampling conditions. Language, Speech, and Hearing Services in Schools , 17 , 187–198. Arnold, H. S., Conture, E.G., & Ohde, R. N. (2005). Phonological neighborhood density in the picture naming

whether ND may simply cease to influence production at the phonological level at a certain age due to more influential factors (e.g., phonotactic probability). Experimental studies should also be conducted with different clinical populations such as children with word- finding impairment in order to examine any performance differences. Conclusion In conclusion, this study found that preschool children retrieved the lexical-semantic representations of words with high ND more accurately than those with low ND. This revealed a facilitative nature of the lexicon in terms of semantic accuracy. A similar result was found regarding phonological accuracy; words with high ND were articulated with a greater degree of accuracy than those with low ND. As such, the degree of phonological similarity in the lexicon appears to impact preschoolers’ production accuracy both at the lexical and phonological level. Appendix A. Experimental stimuli Low neighbourhood density words Neighbourhood density

High neighbourhood density words

Neighbourhood density

wagon guitar brother chicken

1 1 3 3 3 4 4 5 7 8 8 8 9 9 9

drum water

11 11 12 13 13 14 14 14 16 17 20 21 36 41 42

feather ladder shower cloud lemon

finger flower judge twins queen brush space father

teeth green plate

jeep vase

knife three snail

zoo

toes nail

Appendix B. Experimental stimuli control Variable

Means (SD): low neighbourhood

Means (SD): high neighbourhood Statistic

density stimuli 106.67 (174.26)

density stimuli 58.40 (117.41)

t (28) = 0.89, p = 0.38, d = 0.32

Word frequency 1

Positional segment frequency

0.22 (0.07)

0.22 (0.06)

t (28) = 0.16, p = 0.87, d = 0

Biphone frequency

0.004 (0.004)

0.003 (0.003)

t (28) = 0.96, p = 0.35, d = 0.28 t (28) = 1.77, p = 0.08, d = 0.67 t (28) = 0.73, p = 0.47, d = 0.27 t (17) = 0.14, p = 0.89, d = 0.06 t (17) = 0.21, p = 0.84, d = 0.09 t (28) = 1.02, p = 0.32, d = 0.37 t (15) = 0.11, p = 0.90, d = 0.05

Number of phonemes

4.07 (0.65)

3.60 (0.74)

Number of syllables

1.47 (0.52)

1.33 (0.49)

Imageability

612.40 (43.35)

608.33 (79.06)

Familiarity

365.50 (101.02)

377.44 (148.45)

Visual complexity

51.35 (26.85)

41.61 (25.35)

Age-of-acquisition

3.94 (2.18)

4.04 (1.46)

1 Note . While the means for word frequency appear different, upon further inspection it was determined that one word with low ND had a very high word frequency value; when this word was omitted, the average word frequency for words with low ND was 59.73, and the average word frequency for words with high ND was 58.40, helping to explain the lack of significant difference reported here.

23

JCPSLP Volume 15, Number 1 2013

www.speechpathologyaustralia.org.au