Making sense of the maze: Exploring the source of neologistic errors in a case of jargon aphasia

Melanie Moses1,2,3, Lyndsey Nickels2, Christine Sheard3

Royal Rehabilitation Centre Sydney1, Macquarie Centre for Cognitive Science, Macquarie University2, The University of Sydney3

Neologisms

• Typify language in jargon aphasia

• Disagreement re definition and source

• Different definitions: any nonword response (e.g Miller and Ellis, 1987)

unrelated to target Vs phonologically-related (e.g. Buckingham, 1987; Schwartz, et al., 1994)

This presentation….

• Neologism = nonword responses that are unrelated to target.

e.g. ball dEb

• Non-word responses phonologically related to the target = phonological errors.

e.g. ball bIl

Case Study: KVH

• 71-year-old-man

• Left basal ganglia (CVA) in January 2000

• Severe fluent jargon aphasia.

• Wernickes Conduction Aphasia

• Fluent spontaneous speech with ++ perseverative, neologistic & semantic jargon

• Good comprehension at basic conversational level but difficulties at complex level

Aims

• Determine KVH’s language processing breakdown

• Determine the source of KVH’s neologisms

Phonological Output Lexicon

Speech

Phonological Output Buffer

Phonological encoding

Phonological Input Lexicon

Phonological Input Buffer

Acoustic-to-phonological conversion

Auditory analysis

Speech

X

Mild impairment

X

Mild impairment

X

But many phonologically-related errors

can process some phonological information

ConceptualSemantics

Lexical Semantics

Visual Object Recognition System

Phonological Input Lexicon

Phonological Input Buffer

Acoustic-to-phonological conversion

Auditory analysis

Orthographic Input Lexicon

Abstract Letter Identification

Visual feature analysis

Speech PrintPictures, seen objects

X

X

X

Moderate central semantic deficit

Phonological Output Lexicon

Speech

Phonological Output Buffer

Phonological encoding

Lexical Semantics

Orthographic Input Lexicon

Abstract Letter Identification

Letter-sound rules

Visual feature analysis

PrintPictures, seen objects

X

X

X

X

More phonologically-relatedresponses to nonwords & regular words some intact sublexical processing

X

Severely impaired access to phonological form via lexical reading route

Research Tasks

• Picture naming, word reading aloud, word repetition• 126 items, presented twice

• Repetition:– few errors, mainly phonological (real & nonword)

mild phonological encoding difficulties– few neologisms

• Naming & Reading Aloud:– many errors 50% neologistic – large proportion of phonological errors in reading reflects

impaired phonological encoding– imageability effect in naming (Wald = 4.818; p = .028)

semantic impairment.

Where is KVH’s language breaking down?

Phonological Output Lexicon

Speech

Phonological Output Buffer

Phonological encoding

ConceptualSemantics

Lexical Semantics

Visual Object Recognition System

OrthographicOutput Lexicon

Graphemic Output Buffer

Writing

Phonological Input Lexicon

Phonological Input Buffer

Acoustic-to-phonological conversion

Sound-Letter Rules

Auditory analysis

Orthographic Input Lexicon

Abstract Letter Identification

Letter-sound rules

Visual feature analysis

Speech PrintPictures, seen objects

Where do KVH’s neologisms come from?

Let’s first look at the literature…….

Impaired self-monitoring?

• Poor self-awareness of speech errors in jargon aphasia (Marshall et al., 1998)

more susceptible to neologisms

• Poor self-monitoring linked with poor auditory comprehension (Ellis et al., 1983) although this is debatable (Nickels & Howard, 1995)

Can impaired self-monitoring account for KVH’s neologisms?

• Superior self-monitoring in repetition (least errors, few neologisms):

proportionately more errors rejected (Vs. naming or reading)

more likely to reject error than correct response

largest proportion of “don’t know” responses

presence of phonological model in repetition to compare intended with actual response?

But…..

• In repetition: just as likely to reattempt a correct as error response and unable to

successfully self-correct errors. reattempted only 20% of errors, only 1 resulting in correct response

• In picture naming: many neologisms significantly more error than correct responses reattempted more

accurate self-monitoring than repetition?

Relationship between neologisms & self-monitoring not straightforward

KVH’s neologisms can’t be explained in terms of poor self-monitoring alone.

Impaired phonological encoding?

• Neologisms reflect severe distortion of a target at phonological encoding level response contains no target-related phonemes? (e.g. Kertesz & Benson, 1970)

• Phonological distortion of an error from an earlier stage of lexical access (e.g. Nickels, 2001)

(semantic error phonological error)

Can impaired phonological encoding account for KVH’s neologisms?

• Could account for the source of some of KVH’s neologisms

BUT... • he should have produced large numbers of neologisms in repetition as

phonological encoding is common to all 3 tasks

• absence of syllable length effects in any task

primary source of KVH’s neologisms is NOT phonological encoding impairment

Underlying lexical access impairment?• Neologisms fill in a “lexical” gap when word selection fails (Buckingham &

Kertesz, 1976; Butterworth, 1979, 1992).

• Butterworth (1979, 1992) proposed “KC” used back-up “device” which generates neologisms after failure to retrieve lexical target.

• neologisms generated by random assembly of previously produced phonemes – ie. perseveration

• Obeyed English phonotactic rules

• Didn’t obey English phoneme frequency x = no underlying lexical target?

Butterworth (1979, 1992)

• Neologistic errors reflected failed attempt to retrieve the target word at lexical level default to a neologism-generating “device.”

• Phonemic variants of a “device” neologism may be used up to 5 or 6 times string of phonologically similar neologistic responses.

• Example: bklnd – bndIks – ndIks – zndIks – lndIks – zprIks

• These phonologically-related neologisms are well documented in jargon aphasia

Can impaired lexical access account for KVH’s neologisms?

• Neologisms may result from severe impairment in accessing the lexical form of the word.

• Naming = SS POL X

• Reading aloud = OIL SS POL X

• Phonological encoding deficits further impact on performance

• Can access sublexical phonological information in repetition

• Unable to derive sublexical phonological information from written input

Therefore...

• insufficient activation of target lexical representation

phonemes from previous responses assembled to form a neologism.

• neologism fills the lexical “slot” for the missing target (Butterworth, 1979; 1992)

KVH’s neologisms could reflect an underlying impairment accessing the lexical form of the word via both spoken or written modalities.

Perseverative influence on neologisms

• Majority of KVH’s neologistic errors in all tasks were perseverative

(Repetition: 67%; Reading: 83%; Naming 64%).

• Suggests production of neologisms strongly linked to a process of perseveration

KVH’s perseverative error patterns

• KVH mainly produced phoneme perseverations in all tasks

• But different types in Repetition Vs Picture Naming & Reading Aloud

Repetition

Nail n1l

Star st1l

Short duration, phonologically related to target

Neologistic perseverative strings

• Picture naming:

psn pIs pIs pIsn frn pI (bowl) (glasses) (carrot) (desk) (cannon)

• Reading aloud: sibr sig sua sup sug (zebra) (chain) (apple) (carrot) (mountain)

Long duration, unrelated to target

Consistent with neologistic strings in literature on jargon aphasia

KVH’s perseverative errors

• KVH’s perseverative errors reflect his different levels of processing breakdown,

(phonological encoding in repetition, lexical access in reading aloud and picture naming)

• Consistent with recent research on perseveration (Cohen & Dehaene, 1998, Martin et al., 1998, Moses et al 2004, Hirsh, 1998)

Conclusions• KVH’s neologisms most likely reflect impaired activation of phonological forms

via the semantic system Consistent with some research (e.g. Butterworth, 1979, 1992; Simmons and

Buckingham, 1992)

Contradicts others proposing neologisms reflect severe underlying phonological encoding difficulties alone (e.g. Kertesz and Benson, 1970; Lecours and Lhermitte, 1969)

• KVH’s neologisms typical of jargon aphasia

• Errors are consistent with Butterworth’s (1979, 1992) neologism generator theory

• Strong link between KVH’s production of neologisms and phoneme perseveration

Future Directions

• Investigate alternative accounts for production of neologisms e.g. substitution of phonemes based on phoneme frequency (Butterworth, 1992)

• More detailed discussion of nature of KVH’s perseverative errors and links with neologisms

• Replication across series of individuals with jargon aphasia

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