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The Challenge of a Reading Machine for the Blind (1944). Reading machine conception, 1969. optophone. scan text with stylus, arbitrary complex sounds, 1 per letter shape.
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The Challenge of a Reading Machine for the Blind (1944) Reading machine conception, 1969 optophone scan text with stylus, arbitrary complex sounds, 1 per letter shape Failed, because: Discriminability alone is not enough; code on speech needs to be compatible with speech. Minimally, must have the speed of speech. Lessons: A useful reading machine would have to (i) produce speech, (ii) be based on letter identity, not shape
The spectrogram and the pattern-playback Frequency (Hz) Time (s)
Context-conditioned variability of speech perception The same thing means different things Different things mean the same thing Nothing means something context-conditioned variability originally the problem, ultimately the solution
“BAG” 70 muscles of speech Is speech perceived by reference to how it is produced? a g Co-articulation of gestures produces acoustic variability b Invariance is in articulation, not acoustics Object of perception is gesture, not sound ƒrequency time producing any single phoneme involves ≈ 70 articulation motor invariance must be abstract given that motor commands are variable phonation respiration
Dynamics of self-organization, intrinsic timing, articulatory phonology Basic phonological unit: articulatory gesture, a dynamical system with a characteristic set of parameter values. An utterance: an ensemble of potentially overlapping gestural units constrictions variable in location, degree “execution” dynamics “planning” dynamics coordinate transformation articulators tract variables perceive gestures intended gestures [Phonetic Module] articulatory dynamics
3 mos No. of Sucks per minute No. of Sucks per minute Time Time 8 mos Categorical Speech Perception in Infants Initial babbling: all phonemes (Dutch, Zulu, Farsi, …) • Growing sensitivity to native phonemes and insensitivity to non-native phonemes 1st year • Experiment with Japanese babies: dishabituation habituation La La La La La Ra Ra La ≠ Ra habituation continues habituation La La La La La Ra Ra La Ra
Why might a child have difficulty reading? Can’t distinguish letters, a visual perception problem? Can’t register order of letters and words, a visual representation problem? Can’t scan letters and words properly, an eye control problem? Can’t hear the sound contrasts that distinguish words, an auditory perception problem? Can’t link letters to their speech sounds, an associative learning problem? Can’t learn the spelling rules, an (English) orthography problem?
/a/ ƒrequency sound energy time /g/ /b/ Haskins’s answer: reading is hard because speech is easy /a/ throughout /b/ first 2/3 /g/ last 2/3 /a/, /b/, /g/ overlap in middle “BAG” Would-be-reader’s challenge: Gain awareness that spoken words break apart into distinct abstract segments (phonemes) Can’t explicitly segment words into phonemes, a phonological awareness problem? Then: Has basis for learning that letters stand for phonemes—the meaningless elements that make up the words of the spoken language. The Alphabet Principle
Does phonology’s role in reading depend on the writing system? (orthographic depth hypothesis; Serbo-Croatian, Hebrew, English, Chinese) word or nonword? fluent bi-alphabetical reader Phonological Coherence Hypothesis Universal Phonological Principle
Can we reveal the reading network through fMRI and related tools? phonological semantic visual word form component circuits, hypothesized roles Can we reveal improvement in an under-engaged network with training? Normal rhyming task Dyslexic phonological training