Thestages ofintegration leading fromlocal feature analysis toobject recognition wereexplored inhuman visual cortex byusing thetechnique offunctional magnetic resonance imaging. Herewereport evidence forobject-related activation. Suchactivation waslocated atthelateral-posterior aspect oftheoccipital lobe, just abutting theposterior aspect ofthemotion-sensitive areaMT/V5,inaregion termed the lateral occipital complex (LO). LOshowedpreferential acti- vation toimages ofobjects, compared toawiderangeof texture patterns. Thisactivation wasnotcaused byaglobal difference intheFourier spatial frequency content ofobjects versus texture images, since object images produced enhanced LOactivation compared totextures matched inpowerspectra butrandomized inphase. Thepreferential activation toob- jects alsocould notbeexplained bydifferent patterns ofeye movements: similar levels ofactivation wereobserved when subjects fixated ontheobjects andwhentheyscanned the objects withtheir eyes. Additional manipulations suchas spatial frequency filtering anda4-fold change invisual size didnotaffect LO activation. Theseresults' suggest thatthe enhanced responses toobjects werenotamanifestation of low-level visual processing. A striking demonstration that activity inLOisuniquely correlated toobject detectability was produced bythe"Lincoln" illusion, inwhichblurring of objects digitized intolarge blocks paradoxically increases their recognizability. Suchblurring ledtosignificant en- hancement ofLOactivation. Despite thepreferential activa- tion toobjects, LO didnotseemtobeinvolved inthefinal, "semantic," stages oftherecognition process. Thus,objects varying widely intheir recognizability (e.g., famous faces, commonobjects, andunfamiliar three-dimensional abstract sculptures) activated ittoasimilar degree. Theseresults are thusevidence foranintermediate linkinthechainofpro- cessing stages leading toobject recognition inhumanvisual cortex.

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Object-related activity revealed byfunctional magnetic resonance imaging inhumanoccipital cortex

This largely.theoretical discussion attempts to show how the "factors" identified in factor-analytic studies of cognitive abilities can be interpreted. in.termS of current theories anu perimental work in cognitive pSychology. After consideration of the drawbacks of such psychometrically-derived theories of cognitive abilities as those of Guttman, Cattell, and. Guilford,, appeal is made to E. B. Hunt's ".distributi/e .1.umory", model and A. Newell's concept of the "production system" asNossiY hnses for developing an alternative theory. ',Such, a theory of cognitive abilities rests upon the individual differences displayed 'in the parametei-sothe tasks found in typical tests of intelligence. As a first step toward developing a \ew "structure of intellect" model, a detailed subjective analysis is made of the cognitive processes involved in two tests designed to' measure each of the 24 factors in the.1963 version of the Kit of.ReferenCe Tests for .Cognitive. This analysis\is made by systematic coding of aspects of these tasks according to a scheme for relating -these features tojhe distributive memory model and to the producttp:system concept. It is hypothesized:that factor-analytic common factors arise when two or.mare tasks share features in which there are individual differences with respect to (1) the types and contents of MemorY stores involved, (2) the types and 'sequences of/cognitive operations reqUiredand cognitive strai,egies employed by individual subjects, and (3) the types of ,responses elicited. It is claimed that. Crum this point of view, cognitive tasks are. complex, and cognitive factors resist classification by aay rigid taxonomy such as Guilford's Structure of Intellect model'; there are probably no such things as truly "pure" factors. It is held that the study of individual differences in abilities canProfit greatly if it Ls closely tied to the experimental analysis of particular cognitive 'tasks; a t the. -same time, work in the experimental tradition should pay close 'attentiot-Cotthe problem of identifying sources of variance that are due to indiVidual differences in task parameters.

/pdf/psychometric-tests-as-cognitive-tasks-a-new-structure-of-4gepqv58cy.pdf

Christopher G. Burns

Papers

Electrophysiological Correlates of Intellectual and Emotional Intelligence