How spatial attention modulates reading aloud and lexical decision: Evidence from Italian neglect dyslexia patients

2. NEGLECT DYSLEXIA (ND) LESION: RIGHT INFERIOR PARIETAL LOBULE (Bisiach & Vallar, 2000; Vallar et al., 1998) NEGLECT DYSLEXIA: SINGLE WORD READING (egocentric coordinate frames) TARGET: ALBERO �tree� (Ellis et al. 1987) SUBSTITUTION: POBERO OMISSION: BERO ADDITION: COSBERO

3. DISSOCIATIONS L�davas et al. (1997, Neuropsychologia): Simple words and nonwords presented centrally (9 patients) POOR READING ALOUD BUT PRESERVED LEXICAL DECISION AND SEMANTIC JUDGEMENT

4. Explanations Reading aloud differs from lexical decision (semantic judg. and associations) for: Diffculty: lexical decision is easier than reading aloud and requests less information from the left side (guessing strategy). The different involvement of spatial co-ordinate frames (Vallar et al., 1996). The differential use of reading routes (Ladavas et al., 1997): DRC model (Coltheart et al., 2001).

6. The present study Aimed at specifying in further detail the preserved lexical processing in patients with left ND by exploring in LD tasks, the effect of morpho-lexical variables, which influence the performance of Italian unimpaired subjects.

7. EXPERIMENT 1Morphologically simple words and nonwords Dissociations between reading aloud (RA) and LD in neglect dyslexia patients: the same stimuli presented to six patients for both RA and LD (Arduino et al., 2002, Cognitive Neuropsychology). Untimed presentation. LD accuracy: The six patients were compared to 12 controls (matched for age, sex and educational level) Lexical effects in LD: four patients� LD performance was compared to that of non neurological younger adults. Timed presentation (500 or 700 ms.)

10. ESP. 1LD with timed presentation (500 ms.): 4 patientsHigh and Low frequency words: % correct answers. High-frequency words are recognized faster and with less errors than low-frequency words (Colombo, 1992, JEP:HPP; Burani et al., 2002, Brain and Language)

11. EXP. 1 LD with timed presentation (500 ms.): 4 patientsNonwords with High/Low frequency neighbor: % errors

12. LD: non neurological subjects (Arduino & Burani, accepted, JPR) Stimuli: the same Participants: 49 university students Dependent variable: RT and errors

13. EXPERIMENT 2Morphologically complex words and nonwords Dissociation between RA and LD in neglect dyslexia patients: the same stimuli presented to six patients for both RA and LD (Arduino et al., 2002). Untimed presentation. LD accuracy: The six patients were compared to 12 controls (matched for age, sex and educational level) Lexical effects in LD: three patients� LD performance compared to non neurological younger adults. Timed presentation (700 ms.)

14. A) 88 suffixed derived words (Burani & Thornton, 2002, Linguistics). All words were low frequency 44 with HF root (CONSUM-ISMO �consumerism�) 44 with LF root (SIMBOL-ISMO �simbolism�) EXP. 2

16. EXP. 2LD with timed presentation (700 ms.): suffixed derived words Burani & Thornton (2002): less errors in deciding upon words with high-frequency root.

17. EXP 2LD with timed presentation (700 ms.): morphologically complex nonwords Burani et al. (1997, 1999); Burani & Thornton (2002): more errors on nonwords that included either one or two constituent morphemes with respect to nonwords with no morphemes

18. Summary

20. CONCLUSIONS Guessing strategy: The fact that morpho-lexical effects also emerged in the patients� LD allows us to discard the hypothesis that the patients adopt a rough guessing strategy in LD. Differential use of the reading routes (Ladavas et al., 1997): LD: good performance because patients made use of the lexical route (no serial processing is required) RA: impaired performance because patients made use of the sublexical route (serial processing, from left-to-right) Moreover For some Italian patients the lexical route is available for reading aloud (Arduino et al., 2002). It is the availability of the lexical route, which makes use of the whole word-form, that allows the patients to process the stimuli correctly.

21. Arduino et al.�s data (2002) may be taken as further evidence that when patients may have access to the entire word-form directly, through the lexical route, their disturbance is ammeliorate because this latter procedure does not require a sequential, from left-to-right, processing. In conclusion The dissociation between reading aloud and lexical decision may be due to the fact that reading aloud requires, at different processing stage, a left-to-right sequential processing that is impaired in neglect patients, whereas it is not required in LD.

22. Some authors have suggested that word processing may involve two anatomically distinct attentional structures: A posterior attentional system which is devoted to the allocation of visual spatial attention across the visual field (necessary for reading aloud, and which is impaired in neglect patients) and a more central anterior attentional system (preserved in neglect patients) which plays a role in lexical/semantic access (see Carr, 1992, American Journal of Psychology, for a review).

29. Exp. 1Percent of neglect errors as a function of error type

30. EXPERIMENT 2Reading aloud morphologically complex words and nonwords

31. Exp. 2 Percent of neglect errors in reading word and nonword targets

33. Exp. 2Percent of neglect errors as a function of error type

34. RESULTS FIVE PATIENTS SHOWED LEXICAL EFFECTS IN READING, WHILE ONE PATIENT DID NOT (A.A.) FEW ERRORS IN READING words vs. nonwords (Exp. 1 and 2) high vs. low-frequency words (Exp. 1) nonwords with no high-frequency neighbor (Exp.1) derived words with high-frequency constituents (root and suffix). (Exp. 2) morph. complex nonwords with real root and suffix (Exp. 2)

41. Length effect. Percentage of neglect errors to 5-6 vs. 7-11 letter targets (data from Exp. 1 and 2).