Reading words

What has been found in relation to writing and reading?

• Evolutionarily unexpected, experience dependent abilities → surviving writing dates back to around 3500 BC

• 6.6 million adults are functionally illiterate in England

• Writing represents units of spoken language (words, syllables, sounds).

What has been found about visual word processing and understanding of language?

• We read words in many forms, and we extract or generalise the typical features → E.g. many fonts, orientations

What has been found in visual word processing when words are jumbled in sentences?

First and last letter only needed to identify word, focus on whole words not every single letter.

Word recognition comes from shape

What is visual word form?

• Abstract level of representation → words contain typical set of features that the visual system can use to recognise word

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What has been found in relation to accessing visual word forms and serial vs global recognition?

• Global recognition in RVF/LH

• Words presented in RVF processed faster due to global rapid visual recognition in LH

• LVF/RH processing more serial, words recognised by identifying letters and sharing with LH for word identification

What is the triangle model of lexical knowledge?

• Posits three main centres or nodes → orthographic, phonological and semantic representations.

• Nodes interconnected and can be simultaneously activated in given task or can influence each other.

Where is the visual word form area?

• In the fusiform (occipitotemporal) gyrus

What does the visual word form area respond to?

• Words more than false fonts or consonant strings (chair vs ckmn)

• Upper and lower case equally → chair vs CHAIR vs ChAir

• Real words more than non words sounding the same → taxi> taksi

• Orthographic identity of the word

What has been found from fMRI in relation to visual word form area and respond to LVF/RVF presentation (McCandliss et al, 2003)?

• VWFA in LH responds equally strongly to right of left visual field presentation

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• Suggests that word recognition or identification is performed in the LH in typical readers.

What did Dehaene and Cohen find in a study comparing activity in VWFA in literates, illiterates and ex-illerates from different countries?

• VWFA becomes specialised for visual word recognition

• Experience modulates brain development

• Illiterates have higher activation for faces, house and tools.

In typical adults what else also activates the VWFA?

Auditory words and object naming → suggests region has some role in visual object processing.

Blind braille readers also have word area (no selectivity for vision).

How might auditory input also lead to activations in VWFA?

• Automatic links between nodes are established with learning, so sounds also activate VWFA.

  

• VWFA results from developing reading expertise, but may not be exclusively involved in reading or visual processing

What route is taken in the brain when sounding out non words?

• Visual input → VWFA ←→ phonological representation and motor command to say sounds

• No meaning activation

What route is taken in the brain when reading words silently?

• Visual input → VWFA ←→ phonological representation and semantic representation. Ventral route

• Less of dorsal route

• If move tongue while reading → dorsal route will be activation → motor system while reading

What route is taken in the brain when reading words out loud?

• Activation of both dorsal and ventral route

• Visual input → VWFA → semantics → phonological and motor representations

What is developmental dyslexia?

• Difficulty in learning to read → below standard appropriate to age

• No apparent issue with spoken language

• Hereditary component

• Phonological impairment → decomposing words into individual sounds, making sound judgements

What deficits are involved with developmental dyslexia?

• Non word repetition

• Naming pictures

• Phonological working memory

• Rhyming

How is phonological awareness impaired in developmental dyslexia?

This can be seen as a problem of sound decoding, but it probably also involves some aspects of phonological working memory, i.e., the ability to hold and manipulate sounds in working memory

What has been shown in the brain for dyslexic children compared to controls?

• Deactivation in the reading network, particularly the phonological route

• Often, overactivation in left inferior frontal gyrus

• Differential grey and white matter volume: anatomical structures and connections

How are improvements seen in some dyslexics?

• Adults may develop alternative strategies and networks to read

• Hypothesised → RH assumes some of the functions performed by LH in typical readers

Which area of the brain do adult dyslexics show overactivation in?

Broca’s area (IFG)

What is acquired phonological dyslexia (due to stroke)?

• Fine visual lexicon and comprehension but can’t pronounce unfamiliar words

• Non words misread as familiar word

• STM for speech sounds and manipulation of sounds

• Impaired grapheme to phoneme conversion in reading or writing → struggles to translate written letters or letter combinations (graphemes) into corresponding speech sounds (phonemes)

What did Racpsak et al find in a study of non word reading and phonological dyslexia?

• Misreading of words → e.g. doop read as droop, dusp read as dust

How do patients with phonological dyslexia perform in tests where they have to tick items with same sounds?

• Tick words such as duet, cruet

• Don’t recognise quay and key is same sound