LCS 11: Cognitive Science Aim to get data by end of this week - PowerPoint PPT Presentation

Agenda ֠ Upcoming talks Pomona College ֠ Presentations LCS 11: Cognitive Science ֠ Aim to get data by end of this week ֠ Meetings next week Reading and the brain ֠ Group presentations May 1, 6 & 8 ֠ Aphasia ֠ Broca Jesse A. Harris ֠ Wernicke ֠ Alexia April 15, 2013 ֠ Eye movement basics ֠ The brain’s letterbox ֠ Writing response # 4, due Friday April 19 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 1 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 2 Lorraine Tyler William Marslen-Wilson The Neurobiology of Language: Syntax and Semantics Cross-linguistic Contrasts in Morphological Systems: Neurobiological Perspectives Current research on the neurobiological foundations of human language suggests that it is mediated by a coalition of two Despite 150 years of study, the properties of the neural language overlapping systems. A distributed bihemispheric system, largely system remain unclear. I will discuss studies involving behavioural shared with our primate relatives, provides a social and and neuroimaging data on spoken language comprehension. interpretative framework for language comprehension, as well as Combining these types of data from healthy people with basic mechanisms for mapping sounds onto lexical meanings. A comparable data from chronic stroke patients with left hemisphere specialized left hemisphere system, possibly unique to humans, lesions, provides the key ingredients for determining the essential supports core combinatorial functions underpinning morphosyntax. neural networks in- volved in the syntactic and semantic analysis of In recent neuroimaging research in English, Polish, and Arabic we spoken language. investigated how di ff erent types of morphological process (broadly Thursday at 4:15PM, Edmunds 101 de fi ned as in fl ectional and derivational) interface with these two systems, and whether this di ff ers across languages. Friday, April 19: 12 noon, Lunch provided, Edmunds 101 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 3 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 4

Aphasia Broca’s aphasia (1861) Aphasia ◮ Leborgne (age 21; single word Language disorder produced by brain word ‘Tam’) and Lelong (age 86; damage 5 words) Damage to speci fi c areas associated ◮ Major speech production with speci fi c types of de fi cit. di ffi culty 1. Broca’s (production) ◮ Other cognitive functions spared 2. Wernicke’s (receptive) ◮ At autopsy, found lesion in left 3. Conductive frontal lobe Paul Broca (1824–1880) Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 5 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 6 Broca’s aphasia Broca’s aphasia Example of a Broca’s aphasic: ◮ Speech is slow and labored http://www.youtube.com/watch?v=f2IiMEbMnPM ◮ Utterance are not complex Consider watching this clip at home: ◮ Almost no “function words” like to , for , the , etc. http://www.youtube.com/watch?v=NUTpel04Nkc ◮ Yet, words appear to be meaningful and on-topic ◮ In addition, awareness of de fi cit What do you notice about the patient’s speech? Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 7 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 8

Wernicke’s aphasia (1875) Wernicke’s aphasia ◮ Another type of aphasia, termed “sensory aphasia” Wernicke’s aphasia production ◮ No signs of speech production http://www.youtube.com/watch?v=aVhYN7NTIKU di ffi culty Wernicke’s aphasia comprehension ◮ Lack of comprehension, both in http://www.youtube.com/watch?v=dKTdMV6cOZw the utterance produced and reception of speech. ◮ At autopsy, found lesion in left posterior temporal gyrus. Carl Wernicke (1848–1905) Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 9 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 10 Lesion sites Recap Deficit Remaining Lesion site capacity Production, Comprehension, Frontal lobe Broca agrammatism awareness Wernicke Comprehension, Speech fl uent Posterior Sensicality, temporal Awareness gyrus Table: Comparison of aphasia types ◮ Broca’s area: left temporal lobe, anterior to primary motor cortex ◮ Wernicke’s area: Posterior portion of fi rst temporal gyrus Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 12

Conduction aphasia Experiments on aphasic patients ◮ Very rare type of aphasia Non-reversible sentences ◮ Damage to the arcuate Can utilize our world and semantic knowledge to infer the fasciculus, a neural pathway likely relations between words. thought to connect Wernicke’s (3) The book that the girl is reading is yellow area and Broca’s area (disputed) ◮ Both comprehension and production seem relatively Reversible sentences spared Relations between words cannot be determined without help ◮ Di ffi culty repeating speech from the syntax. ◮ Make speech errors and try to (4) The horse that the bear is kicking is brown correct them, usually with much di ffi culty Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 13 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 14 Experiments on aphasic patients Experiments on aphasic patients Predictions ◮ Caramazza and Zurif 1976 tested three di ff erent kinds of aphasics, as well as a control Broca’s If Broca’s aphasics only have a production de fi cit for ◮ Presented subjects with reversible and non-reversible syntactic processing, they should be able to understand complex sentences (just not produce sentences them). Thus, they should be able to perform well on ◮ From two pictures, asked to pick the appropriate both reversible and non-reversible sentences. depiction of the sentence Wernicke’s Predicted to have across the board di ffi culty, due to global de fi cit in comprehension. Non-reversible Reversible Non-reversible Reversible Wernicke Chance Chance Wernicke Chance Chance Broca Good Chance Good Good Broca Table: Performance across di ff erent aphasic groups Table: Expectations across di ff erent aphasic groups

Experiments on aphasic patients Geschwind’s 1965 model of language processing ◮ Evidence that all comprehension capacity for Broca’s aphasics is not spared. ◮ How might we make sense of this pattern? What might aphasics be doing to process the comprehend non-reversible sentences that would fail when attempting to process reversible sentences? Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 17 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 18 Reading The eye Retina Neural sheet at back of Reading processes involves by various factors, including eye consisting of photoreceptors in 1. Acuity limitations on the eye various densities. 2. Rapid movements to overcome such limitations 3. Decoding of orthographic forms into phonetic ones Fovea 4. Access meaning and integration into sentential and High concentration of discourse context cones – photoreceptors responsible for visual acuity, constituting 15° of visual fi eld. Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 19 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 20

Reading Saccade Ballistic eye movements that propel the eye to another fi xation point. Perceptual span Asymmetric perceptual window during reading: 3–4 letters to left; 7–8 to right. Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 22 Reading Reading

Alexia Pure alexia Recognize letters as letters, but incapable of naming or using them to recognize words. ◮ Other visual and verbal capacities are largely spared. ◮ Able to recognize numbers! ◮ Damage to left occipto-temporal Joseph Jules Déjerine area (1849–1917) Dehaene, 2009: Fig 2.1 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 25 � “Why should all human beings have this built-in facility for reading, when writing is a relatively recent cultural invention?” � “How, then, did the visual word form area of the human brain arise?” Oliver Sacks (b. 1933) Dehaene, 2009: Fig 2.1 Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 28

Writing response 4, due Friday, 19 April In previous classes, we’ve discussed the role of biases in cognition. According to Eagleman, biases are, to some extent, what makes us smart by providing some order in perceptual � The brain constrains writing chaos. In the unit on language, we’ve seen examples of bias in systems by accepting only a word leaning - for example, the whole object bias. In your limited types of symbols, those response, please address the following three questions in 2-3 shared with other, more single spaced pages: ancestral forms of visual (1) Can we say that biases encountered during language processing. Thus, shared by all humans – with natural, and acquisition also make us smart? (2) How about restrictions universal, restrictions on that seem to be imposed by our particular native language - for example, whether we have an exact (cardinal) or relative orthographies. number system? (3) How are such restrictions similar or Stanislas Dehaene di ff erent than biases in terms of their cognitive e ff ect? Defend (b. 1965) your position by using concrete examples of biases and restrictions from the readings to illustrate your point. Jesse A. Harris: LCS 11: Cognitive Science, Reading and the brain 29