how spatial attention modulates reading aloud and lexical decision: evidence from italian neglect...

How spatial attention modulates reading aloud and lexical decision:

Evidence from Italian neglect dyslexia patientsLisa S. Arduino

University of Milano-Bicocca, MilanISTC-CNR and Fondazione S. Lucia, IRCCS, Rome

Cristina BuraniInstitute of Science and Technology of Cognition ISTC-CNR, Rome

Giuseppe VallarUniversity of Milano-Bicocca

The Third International Conference on the Mental Lexicon Banff,

Alberta, Canada October 6-8, 2002.

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

UNILATERAL SPATIAL NEGLECT: disturbance in perceiving,representing and orienting attention to the controlesional side of space.

DISSOCIATIONS

• Làdavas et al. (1997, Neuropsychologia): Simple words and nonwords presented centrally (9 patients)

POOR READING ALOUD

BUT

PRESERVED LEXICAL DECISION AND

SEMANTIC JUDGEMENT

xcamposanto

*camposanto= cemetery*campo= field*santo= saint

Severe ND in reading aloud BUT appropriate association (e.g., coffin)

• Vallar et al. (1996, Journal of Clinical and Experimental

Neuropsychology): compound words (E.S.)

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).

Written stimulus

ORTHOG.LEXICON

PHONOL.LEXICON

Phonemic buffer

GPC

rules

Semantics

OUTPUT

The route operates serially:attentional scanning fromleft-to-right

The routeoperates

on the wholeword- form:

NOattentionalscanning

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.

EXPERIMENT 1

Morphologically 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.)

EXPERIMENT 1

A) 40 WORDS: High and Low surface frequency (50%).

B) 72 BISYLLABIC NONWORDS (5-6 letters). Neighborhood frequency (High/Low)

BRISI: CRISINERPE: SERPE

PROCEDURE: untimed (all) timed (4 patients)

LIST: 240 simple words and nonwords

DEPENDENT VARIABLE: errors

Experiment 1RA and LD:

patients% errors

0

10

20

30

40

50

60

P.P. M.N. C.I. F.S. A.A. A.A.

%

RALD

Experiment 1LD: patients vs.

controls % errors

0

5

10

%

P.P. M.N. C.I. F.S. A.G. A.A.

patients

controls

ESP. 1LD with timed presentation (500 ms.): 4 patients

High 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)

80

85

90

95

100%

P.P. M.N. C.I. F.S.

HF

LF

EXP. 1 LD with timed presentation (500 ms.): 4 patients

Nonwords with High/Low frequency neighbor: % errors

0

5

10

15

20

25

%

P.P. M.N. C.I. F.S.

HF LF

BRISI: CRISINERPE: SERPE

LD: non neurological subjects (Arduino & Burani, accepted, JPR)

Stimuli: the same

Participants: 49 university students

Dependent variable: RT and errors

610

620

630

Rt

HF-neigh LF-neigh

Error analysis showed the same pattern

EXPERIMENT 2

Morphologically 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.)

• 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

LIST: 300 morphologically complex words and nonwords

DEPENDENT VARIABLE: errors

PROCEDURE: untimed (all) timed (3 patients)

• B) 138 nonwords (Burani et al., 1997, Yearbook of

Morphology; Burani et al., 1999, Brain and Language)LAMPAD-ISTA (R+S+)

RONDIN-OSTO (R+S-)

ROVOLL-ISMO (R-S+)

MEVIN-OSTO (R-S-)

0

10

20

30

40

50

60

70


%

RALD

0

5

10

15

%


patientscontrols

Exp. 2RA and LD:

patients% errors

Exp. 2 LD: patients vs.

controls % errors

EXP. 2LD with timed presentation (700 ms.): suffixed

derived words

• Burani & Thornton (2002): less errors in deciding upon words with high-frequency root.

02468

101214161820

HF root LF root

% e

rror

s

subjects patients

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

0

5

10

15

20

R+S+ R+S- R-S+ R-S-

% e

rror

i

patients

SummaryThe results of both experiments confirmed that neglect dyslexia patients’ lexical decision: •is preserved compared to reading aloud; •is normal compared to the performance of control subjects;

Moreover the results show that LD:

•is affected by the same morpho-lexical characteristics that influence non neurological younger adults;

•is not related to the severity of neglect dyslexia

0

10

20

30

40

50

60


%

RALD

0

10

20

30

40

50

60

70


%

RALD

Exp. 1

Exp. 2

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.

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.

• 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).

READING ALOUD (ARDUINO ET AL, 2002)

Written stimulus

ORTHOG.LEXICON

PHONOL.LEXICON

Phonemic buffer

GPC

rules

Semantics

OUTPUT

The route operates serially:attentional scanning fromleft-to-right

The routeoperates

on the wholeword- form:

NOattentionalscanning

Demographic features

S/A/E Lesion DurationP.P M/77 - 5 Basal ganglia 5M.N. F/66 - 12 Fs 1C.I. M/47 - 13 FTP 3F.S. M/72 - 8 P 7A.G. M/63 - 13 Fs 4A.A. F/65 - 5 TP 2

Baseline assessment for visual spatial neglect

Letter Canc. Line Canc. Wundt-Jastrow ReadingL R L R L R

P.P 29\53* 0\51 6\11* 0\10 0\20 0\20 2\6M.N 28\53* 0\51 0\11 0\10 3\20* 0\20 1\6C.I. 53\53* 42\51 11\11* 3\10 20\20* 0\20 6\6F.S. 45\53* 3\51 6\11* 1\10 9\20 8\20 6\6A.G. 53\53* 37\51 11\11* 1\10 2\20 2\20 6\6A.A. 53\53* 29\51 6\11* 0\10 7\20* 0\20 6\6

Words (N=38) Nonwords (N=38) Illegal nonwords(N=38)

P.P 0\1 11\15 (73.3%) 2\7 (28.6%)M.N. 4\4 (100%) 13\19 (68.4%) 12\18 (66.7%)C.I. 0\0 2\2 (100%) 7\7 (100%)F.S. 1\1 (100%) 18\22 (81.8%) 7\20 (35%)A.G. 5\7 (71.4%) 15\24 (62.5%) 14\24 (58.3%)A.A. 22\24 (91.7%) 27\33 (81.8%) 19\35 (54.3%)

Reading test (Vallar et al., 1996)

% neglect errors out of the total number of errors

0

10

20

30

40

50

% n

egle

ct e

rror

sP.P. M.N. C.I. F.S. A.G. A.A.

high-frqlow-frq

0

10

20

30

40

50

60

% n

egle

ct e

rror

s


highlow

Exp. 1 HIGH\LOWFREQUENCYWORDS

Exp. 1 NONWORDSWITH HIGH\LOWFREQUENCYNEIGHBOR

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

0

20

40

60

80

100

% n

egle

ct e

rror

s


substitutionsomissions

EXPERIMENT 2Reading aloud morphologically complex words and nonwords

Morpho-lexical reading of nonwords (Burani et al., 1997; 1999;Burani & Thornton, 2000)

LAMPAD-ISTA (root-suffix: R+S+)MEVIN-OSTO (no root and no suffix: R-S-)

Morpho-lexical processing of derived (suffixed) (Burani &Thornton, 2000)

BASS-EZZA (high-freq. root and suffix, HH) “Lowness”BEFF-ARDO (low-freq. root and suffix, LL ) “Mocking”

113 stimuliLIST: 300 STIMULI. DEPENDENT VARIABLE: ERRORS PROCEDURE: UNTIMED AND TIMED (700 msec.).

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

targets

0

10

20

30

40

50

60

% n

egle

ct e

rror

s


wordsnonwords

0

10

20

30

40

50

60

70

% n

egle

ct e

rror

sP.P. M.N. C.I. F.S. A.G. A.A.

HHLL

01020304050607080

%ne

glec

t e

rror

s


R+S+R-S-

Exp. 2 DERIVED (SUFFIXED)WORDS

HH: BASS-EZZALL: BEFF-ARDO

Exp. 2MORPH. COMPLEXNONWORDS

R+S+ LAMPAD-ISTAR-S- MEVIN-OSTO

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

0

20

40

60

80

100

% n

egle

ct e

rror

s



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)

CONCLUSIONS

The two types of neglect dyslexia are differentmanifestations of a single attentional disorder, different in degree.

Relationship between the severity of the attentional disturbance and the presencevs. absence of lexical effects in reading.

BUT: Relationship between the severity of left neglect andlexical effects is specific to the domain of neglect dyslexia, and not extending to other manifestations of the disorder.

Baseline assessment for visual spatial neglect

Letter Canc. Barrage Wundt-JastrowL R L R L R

C.I. 53\53* 42\51 11\11* 3\10 20\20* 0\20 8%

A.A. 53\53* 29\51 6\11* 0\10 7\20* 0\20 53%

Percentage of reading errors committed by the two patientsunder condition of unconstrained time (Exp. 1 and 2)

These results suggest that neglect dyslexia reflects a form of impairment in the spatial allocation of attention or in spatial representation, specific to the domain of the reading system. By and in line with this view, neglect dyslexia has been described in the absence of other manifestations of neglect symptoms for nonverbal material (Bisiach et al., 1990), or involving the one side of space opposite to the one where neglect for nonverbal material is present (Cubelli et al., 1991; Riddoch et al., 1995).

Relationship between error type and lexical eff ects

Exp. 1 Exp. 2 Subst./Omiss.P.P Yes Yes SubstitutionsM.N. Yes Yes SubstitutionsC.I. Yes Yes OmissionsF.S. Yes Yes OmissionsA.G. Yes No OmissionsA.A. No No Omissions

0

20

40

60

80

100

%ne

glec

t er

rors



0

20

40

60

80

100

% n

egle

ct e

rror

s



EXP. 1 (6.0)

EXP. 2 (8.3)

Mean stimuli length

• Within a left-to-right gradient interpretation of left neglect the assumption can be made that the longer is the letter string the more degraded is the internal representation of its left side.

• The increase in omissions with longer letter strings representsa counterpart, in the reading domain of the well known effectof line length in segment bisection: The rightward shift of the subjective midpoint increases with longer lines (Vallar et al., 2000; Bisiach et al., 1983).

•Within this interpretative framework the more material is tobe computed on the left side of the letter string, the greater is the probability of a defective processing, that is of an omissionerror.

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

0

10

20

30

40

50

60

70


% n

egle

ct e

rror

s

5-67-11

The relationship between error types (sub. vs. omiss.) the severity of the attentional disorder and lexical effects also falls along a continuum:

• Large majority of omissions may be associated witha more severe attentional disorder and with the absence of lexical effects in reading.

• A large majority of substitutions may be associatedwith preserved lexical effects and a less severe attentional disorder.

how spatial attention modulates reading aloud and lexical decision: evidence from italian neglect...

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