Brain & Language slides

Word semantics 3DAY 28 Nov 1, 2013Brain & LanguageLING 4110-4890-5110-7960NSCI 4110-4891-6110Harry HowardTulane UniversityCourse organizationThe syllabus, these slides and my recordings are available at http://www.tulane.edu/~howard/LING4110/.If you want to learn more about EEG and neurolinguistics, you are welcome to participate in my lab. This is also a good way to get started on an honor's thesis.The grades are posted to Blackboard.11/01/113Brain & Language - Harry Howard - Tulane University2Review11/01/113Brain & Language - Harry Howard - Tulane University3Linguistic model, Fig. 2.1 p. 3711/01/113Brain & Language - Harry Howard - Tulane University4Discourse modelSyntaxSentence prosodyMorphologyWord prosodySegmental phonologyperceptionAcoustic phonetics Feature extractionSegmental phonologyproductionArticulatory phonetics Speech motor controlINPUTSemanticsSentence levelWord levelHierarchy of categoriesfurniture|chair|benchdomain-level|basic/prototype|subordinate11/01/113Brain & Language - Harry Howard - Tulane University5Basic is specialResponse Times: in which queries involving a prototypical members (e.g. is a robin a bird) elicited faster response times than for non-prototypical members. Priming: When primed with the higher-level (superordinate) category, subjects were faster in identifying if two words are the same. Thus, after flashing furniture, the equivalence of chair-chair is detected more rapidly than stove-stove. Exemplars: When asked to name a few exemplars, the more prototypical items came up more frequently. 11/01/113Brain & Language - Harry Howard - Tulane University6http://en.wikipedia.org/wiki/Prototype_theory6Basic is really specialIt is the highest level at which a single mental image can represent the entire category (you cant get a mental image of vehicle or furniture). It is the highest level at which category members have a similarly perceived overall shape. It is the highest level at which a person uses similar motor actions for interacting with category members. It is the level at which most of our knowledge is organized.11/01/113Brain & Language - Harry Howard - Tulane University7http://www.defendingthetruth.com/topic/11257-what-is-a-basic-level-category/711/01/113Brain & Language - Harry Howard - Tulane University8Early and late visionearly vision is beneath the surface; late vision is on it

811/01/113Brain & Language - Harry Howard - Tulane University9Norman (2002)Constructivist approachventral ~ identificationthe stimulation is inherently insufficient, necessitating an intelligent perceptual system that relies on inferenceperception is indirect/multistage process between stimulation and perceptmemory, stored schemata, and past experience play an important role in perceptionexcels at analyzing the processes and mechanisms underlying perceptionEcological approachdorsal ~ visual control of motor behaviorthe information in the ambient environment suffices and is not equivocal, and thus, no mental processes are needed to enable the pick-up of relevant informationperception is direct/single-stage processno role for memory or related phenomena excels at the analysis of the stimulation reaching the observeraffordances9Lexical semantics 3Visual object identification11/01/113Brain & Language - Harry Howard - Tulane University10Category-specific deficits11/01/113Brain & Language - Harry Howard - Tulane University111111/01/113Brain & Language - Harry Howard - Tulane University12Do you see any difference between (a) and (b)?

12Figure 1. Drawings of (a) nonliving and (b) living things from a patient with herpes simplex encephalitis and a category-specific semantic deficit for living things. From When Leopards Lose Their Spots: Knowledge of Visual Properties in Category-Specific Deficits for Living Things, by H. E. Moss, L. K. Tyler, and F. Jennings, 1997, Cognitive Neuropsychology, 14, pp. 935, 937. Copyright 1997 by Taylor & Francis. Reprinted with permission.Category-specific semantic impairmentsFigure 11.111/01/113Brain & Language - Harry Howard - Tulane University13concrete(picture-able)animateinanimateanimalsplantswild|lionsharkdomestic|catgoldfishinedible|treeflowerfruit & veggie|applebanana??toolstransportprocessedfood|pizzacidermusicalinstrument|pianodrumhammerpencilcarbikeabstractbeliefshame3:1The anatomy of object processing: The role of anteromedial temporal cortexBright, Moss, Stamatakis & Tyler (2005) 11/01/113Brain & Language - Harry Howard - Tulane University1414Semantic feature assignmentTable 11.2manwomanboygirlmarecolthuman++++female+++mature+++11/01/113Brain & Language - Harry Howard - Tulane University15manwomanboygirlmarecoltman322111woman31210boy3202girl311mare31colt3Semantic similarity scoresTable 11.3Features as a network 1excitation11/01/113Brain & Language - Harry Howard - Tulane University16humanfemalematuremanwomanboygirlmarecoltActivation of man will wind up activating female, which is a contradiction.Features as a network 2excitation, inhibition11/01/113Brain & Language - Harry Howard - Tulane University17humanfemalematuremanwomanboygirlmarecoltActivation of man will still wind up activating female, but inhibition will now turn it off.Features as a network 3excitation, inhibition11/01/113Brain & Language - Harry Howard - Tulane University18humanfemalematuremanwomanboygirlmarecoltIn cortex, long-distance connections are excitatory, while short-distance connections are inhibitory.Activation of man will wind up activating female, but inhibition of woman will turn it off.11/01/113Brain & Language - Harry Howard - Tulane University19Correlated feature theoryThe way we go from feature representation to neural organization is by hypothesizing that correlation among the features of an object leads to mutually reinforcing activation (co-activation) in the features' neural representationshared properties are inter-correlated and so become strongly activated and less susceptible to damage,distinctive properties are weakly correlated and so become weakly activated and more susceptible to damage.Performance depends on taskIf the task requires access to the distinctive features of an object, then a deficit for animates will emerge, due to the lesser degree of correlation among their distinctive features.So the CSA proposes that category-specific deficits developfrom damage to a unitary, distributed semantic system, not from damage to anatomically distinct, content-specific stores19Feature network for animatesexcitation, mutually reinforcing activation (excitation) 11/01/113Brain & Language - Harry Howard - Tulane University20headcamelcrocodileduckpenguinzebratorsolegshumpeyesbillstripesInanimate vs. animate, side by sideInanimatefew overlapping and inter-correlated features,relatively more distinctive features,and they tend to be more strongly correlated with one another. inanimate concepts are less easy to confuse with one another.Animatemany overlapping and inter-correlated features (legs, eyes, teeth),few distinctive features (mane, hump, pouch),and they are only weakly correlated with one another. animate concepts are easy to confuse with one another.11/01/113Brain & Language - Harry Howard - Tulane University21ProblemCorrelated feature theory cannot account for other patterns of impairment, such as cases in which artifacts are more poorly identified than living things.11/01/113Brain & Language - Harry Howard - Tulane University22Sensory/functional theoryKnowledge of objects organized into:networks of sensory features: form, motion, color, taste, etc., and networks of functional features: how, when, and where the object is typically used.A CSSD arises when one of these networks is disruptedanimates are mostly comprised of sensory features; inanimates are mostly comprised of functional features. (??)11/01/113Brain & Language - Harry Howard - Tulane University23Domain-dependent hypothesisThe brain has evolved dedicated neural machinery for recognizing and responding to certain categories of objects that have high survival significance:face recognition, predator detection, food identificationThese categories are recognized on the basis of prototypes:A given exemplar (instance) is matched to the best prototype.They are modular, but not necessary localized to a single region (i.e. they could be distributed networks).11/01/113Brain & Language - Harry Howard - Tulane University24Example of patient FAVRead about him/her and the explanation(s) for his/her deficit, Ingram pp. 235-8.11/01/113Brain & Language - Harry Howard - Tulane University25NEXT TIMEQ8More word semantics11/01/113Brain & Language - Harry Howard - Tulane University26