A Better Look at Intelligence

28 VOLUME 11, NUMBER 1, FEBRUARY 2002

Published by Blackwell Publishing Inc.

Silberg, J., Pickles, A., Rutter, M., Hewitt, J., Simo-noff, E., Maes, H., Carbonneau, R., Murrelle,L., Foley, D., & Eaves, L. (1999). The influenceof genetic factors and life stress on depressionamong adolescent girls.

Archives of GeneralPsychiatry

,

56

, 225–232.Sowell, E., & Jernigan, T. (1998). Further MRI evi-

dence of late brain maturation: Limbic volumeincreases and changing asymmetries during

childhood and adolescence.

DevelopmentalNeuropsychology

,

14

, 599–617.

Spear, L.P. (2000). The adolescent brain and age-related behavioral manifestations.

Neuroscience& Biobehavioral Reviews

,

24

, 417–463.

Walker, E., Baum, K., & Diforio, D. (1998). Devel-opmental changes in the behavioral expressionof the vulnerability for schizophrenia. In M.

Lenzenweger & R. Dworkin (Eds.),

Origins anddevelopment of schizophrenia

(pp. 469–492).Washington, DC: American Psychological As-sociation Press.

Watson, C., & Gametchu, B. (1999). Membrane-ini-tiated steroid actions and the proteins that me-diate them.

Proceedings of the Society forExperimental Biology & Medicine

,

220

, 9–19.

Abstract

The Planning, Attention, Si-multaneous, and Successive(PASS) model is offered as analternative to the unidimen-sional conceptualization of in-telligence as a general ability.The unidimensional conceptu-alization has not helped re-searchers and c l in i c iansunderstand variations of cog-nitive functions within specialpopulations such as individu-als with learning disabilities,disorders of attention, or men-tal retardation. Neither has thisconceptualization aided in pro-gram planning for these indi-viduals. PASS is a model ofcognitive function based oncontemporary research in bothcognition and neuropsychol-ogy and provides a theory forboth assessment and interven-tion. This article reviews con-cepts and examples of PASStheory and its application toreading disabilities and men-tal retardation. For example,the article links dyslexia with adeficit in successive process-ing. It also identifies the majordifficulties of individuals withDown syndrome in phonologi-cal memory and articulation.Further research on successive

processing, and planning as itrelates to language, is sug-gested.

Keywords

intell igence; PASS theory;reading disability

The brain consists of a great manymodules that process information moreor less independently of each other. Itseems likely that it will be easier to dis-cover how one of those modules worksthan to explain the functioning of thebrain as a whole. (Frith, 1997, p. 5)

This quotation questions the va-lidity of the notion that there is ageneral factor of intelligence. Muchas the organs of the body are spe-cific and diverse in their functions,the brain, although admittedlyworking as a whole, cannot be con-ceived to have one general intelli-gence function. Arguments againsta general factor of intelligence ariseboth from logical considerationsand from clinical observations.Clinically, in cases of brain dam-age, specific cognitive functions areoften spared while others remainimpaired. In addition, individualswho have significantly damagedfrontal lobe functions may havenormal IQs, despite the fact that

the frontal lobes are essential forhigher cognitive processes. Simi-larly, some dyslexic children havehigh IQs despite their significantdifficulties in reading.

Examples such as these chal-lenge the usefulness of a one-dimen-sional notion of general intelli-gence, be it conceptualized asmental energy or speed. A general-ability view leads to different ques-tions and measures of ability than aview that intelligence is made upof multiple and interdependentcognitive processes. Multidimen-sional views of intelligence aresuggested by the seven modules ofintelligence posited by Gardner(1983), the triarchic theory of Stern-berg (1985), and the Planning, At-tention, Simultaneous, and Succes-sive (PASS) theory my colleaguesand I have proposed.

As its name suggests, the PASStheory refers to four kinds of com-petence. First, planning processesare required when an individualmakes decisions about how tosolve a problem, carry out an activ-ity, or compose a narrative. Thiscomponent involves goal setting,as well as anticipating and moni-toring feedback. Second, attention,or arousal, is the process that al-lows a person to selectively attendto some stimuli while ignoring oth-ers, resist distractions, and main-tain vigilance. Third, simultaneousprocessing integrates stimuli intogroups. As a result, stimuli areseen as whole, each piece being re-lated to the others. Fourth, succes-sive processing includes integrat-ing stimuli in a specific serialorder. For example, to understand

A Better Look at Intelligence

J.P. Das

1

Developmental Disabilities Centre, University of Alberta, Edmonton,

Alberta, Canada

Copyright © 2002 American Psychological Society

CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 29

English syntax, an individual hasto process words in order to deter-mine their grammatical function.The PASS theory was developedwith the intention of predictingand explaining normal as well asatypical cognitive functions. Thetheory links the four processeswith particular areas of the brain,following the work of Luria (1966).

NEUROPSYCHOLOGICAL LINKAGE

Luria (1966) described humancognitive processes within a frame-work of three functional units: onethat regulates arousal and atten-tion, a second that codes informa-tion using simultaneous and suc-cessive processes, and a third thatprovides for planning, self-moni-toring, and structuring of cognitiveactivities. According to Luria, thefirst unit is located in the brainstem and its connections with thefrontal lobes; the second is in theback of the cortex in occipital, pari-etal, and frontotemporal regions;and the third is located in the fron-tal lobes (see the next section).

Although Luria’s work was ablueprint for the PASS model, mycolleagues and I have also consid-ered recent neuroimaging researchthat has revealed a wealth of newinformation about the roles variousbrain structures play in humancognition (e.g., Posner, 1993). Forinstance, research has shown thatattention is divided into four sub-processes: the engagement, mainte-nance, disengagement, and shiftingof attention (Posner, 1993, p. 644).These functions are spread overseveral regions of the brain, includ-ing the posterior parietal cortex,frontal eye-field, and brain-stemreticular formation. The addition ofthe parietal cortex, which regulatesspatial processing, to the functionallocation of attention is necessary inorder to account for aspects of spa-

tial attention. These findings sup-port two of Luria’s notions: (a) acomplex function cannot be strictlylocalized in one region of the brain,and (b) spatial information is pro-cessed in the occipital-parietal re-gion.

PASS THEORY IN BRIEF

The PASS theory provides amodel to conceptualize human in-tellectual competence. My col-leagues and I first presented it com-prehensively more than 25 yearsago (Das, Kirby, & Jarman, 1975). Atthat time, the model included threeprocesses: planning, simultaneousprocessing, and successive process-ing. Since that time, we have addedthe component of attention-arousaland elaborated the planning com-ponent (Das, Kar, & Parrila, 1996;Das, Naglieri, & Kirby, 1994).

Over the years, we have writtenabout the implications of the modelfor understanding various cogni-tive processes, such as reasoning,memory, imagery, and language.We have also developed practicalapplications of the model, includ-ing the Cognitive Assessment Sys-tem (CAS; Naglieri & Das, 1997)and the PASS Reading Enhance-ment Program (PREP), a remedia-tion program for reading difficul-ties (Das, 1999). Another successfulapplication of the model is a pro-gram for remediating arithmeticdifficulties, which are related to de-ficiencies in planning. Throughoutthe theory’s 25-year developmentalperiod, Luria has been an influenceon how we have framed researchquestions, designed assessment de-vices, and constructed interven-tion procedures.

Figure 1 is a diagram of thePASS model, showing the basic di-vision of input, processing, andoutput (Das et al., 1994). First, in-put information is received fromexternal sources through the senses

and from internal sources; internalcognitive information such as im-ages, memories, and thoughts be-come part of the input. External in-put information can be presentedserially or concurrently. When thesensory information is sent foranalyses, the four central pro-cesses (planning, attention-arousal,simultaneous processing, and suc-cessive processing), as well as theknowledge base, become active.Similarly, output can occur in twoforms, serial and concurrent.

Consistent with Luria’s (1966)framework, the PASS componentsare broadly associated with fourdifferent parts of the brain (Das etal., 1994). Planning is located in thefrontal lobe. Specifically, cognitivefunctions such as reasoning are at-tributed to the prefrontal dorsolat-eral cortex, whereas socially rele-vant decision making may be thefunction of the fronto-orbital cor-tex. Planning is required when anindividual makes decisions rang-ing from specific actions to generalplans such as revising life’s goals.Planning also guides how peoplefocus their attention and use simul-taneous and successive processeswhen required.

The attention-arousal compo-nent is more difficult to locate.Arousal keeps people awake andalert and is associated with arousalactivities in the brain stem as wellas with inhibitory activities in thethalamus. The mobilization of at-tentional resources, however, is thefunction of the frontal lobes andclosely connected to planning.

Simultaneous and successiveprocessing are located in the poste-rior region of the cortex. Simulta-neous processing is broadly associ-ated with the occipital and parietallobes, whereas successive process-ing is associated with the frontal-temporal lobe. All four processesmust be active in the context of anindividual’s knowledge base.Knowledge is built upon the baseof past experiences and includes



both formal and spontaneously ac-quired knowledge. It is essentialfor providing the background forinformation to be processed. It is asif the PASS processes are floatingon a sea of knowledge; without thewater, they cannot operate and willsink. Knowledge can be of twokinds: tacit (spontaneous, experi-ential) and explicit (formal, in-structed).

The last component of the PASSmodel is output, which is ex-pressed in behavior. Donald (1991)has suggested that there are threeoutput modes: movements, mimet-

ics, and language. Movements in-clude both gross and fine move-ment; mimetics comprises dance,music, theatrical poses, and bodylanguage; and language includesoral and written language, as wellas graphs and signs.

ASSESSMENT OF PASS PROCESSES: AN

ALTERNATIVE TO IQ TESTS

The CAS (Naglieri & Das, 1997)is a measurement instrument that

can be used to determine an indi-vidual’s competence and level ofcognitive functioning. It can beused, for example, to diagnoselearning strengths and weaknesses,learning disabilities, attention defi-cits, mental retardation, and gifted-ness. Scores on this instrument canbe used to determine whether anindividual meets the eligibility cri-teria for state or federal interven-tion programs, and more generallyto guide decisions on the appropri-ateness of treatments and instruc-tional programs.

The CAS is an individually ad-ministered test designed for chil-dren and adolescents ages 5through 17 years. The test consistsof 12 subtests, three for each of thefour PASS scales. There is also a to-tal score called the Full Scale. Thetests vary in content: Some are ver-bal, some are not; some involvememory, others do not. For exam-ple, a Planning test is MatchingNumbers, in which the task is tofind and underline two identicalthree-number sequences in a rowof six three-number sequences(249, 371, 539, 467, 539, 749). An At-tention test is Receptive Attention,in which the task is to underlinepairs of letters that are physicallythe same (e.g., AA, but not BA) orthat have the same name (e.g., aA,but not eA). In the SimultaneousVerbal-Spatial Relations task, chil-dren are presented with six draw-ings and a printed question thatmay be read aloud by the examiner(e.g., “Show me the picture that hasa triangle to the left of a circle.”). ASuccessive processing task is Sen-tence Repetition and Questions, inwhich the child listens to a sen-tence spoken by the examiner andanswers a question (e.g., “Thebrown greened the red yellow.Who greened the red?”).

Some evidence of the usefulnessof this instrument is presented inthe following sections, whichshow how PASS can help in clari-fying the mental processes not only

Fig. 1. Diagram of the Planning, Attention, Simultaneous, and Successive (PASS) model.



able in nonreading tasks as well(i.e., in distal processes)? Proximalprocesses whose impairment couldresult in dyslexia include phono-logical processes, which deal withthe sound structure of language(e.g., Wagner & Torgesen, 1987),and orthographic processes thatare essential for recognizing an ar-ray of letters as a word. Ortho-graphic processes are involved inpronunciation and spelling ofwords in which the same spellinghas different pronunciations (e.g.,

bead

and

dead

). The four PASS pro-cesses are distal processes thatcould be related to dyslexia. Theseprocesses enable individuals tolearn the sound system and orthog-raphy of their language, as well asstrategies for the appropriate ap-plication of phonology and orthog-raphy. On the basis of researchbased on our theory, we can distin-guish between individuals whohave specific reading disability(dyslexics) and those who are sim-ply generally poor readers. Indi-viduals with true dyslexia have aspecific deficit in successive pro-cessing. Their reading problemsare specific: They make phonologi-cal errors while reading real ormade-up words or are slow inreading them (i.e., are slow decod-

Table 1.

Case studies of attention deficit disorder

Scores

Case Age Country Gender Reason for referral Planning Attention Simultaneous Successive

1 12 United States Male Attention deficit disorder 115 87 110 1172 8 South Africa Male Attention deficit disorder 98 84 110 98

Table 2.

Case studies of cognitive deficits

Scores

Case Age Country Gender Reason for referral Planning Attention Simultaneous Successive

1 14 Spain Male School failure 69 94 76 812 10 United States Male Reading disability 117 118 94 813 16 India Female School failure 71 71 103 100

of normal children, but also of chil-dren and adults with reading diffi-culties and mental retardation.

CLINICAL USES OF THEPASS MODEL AND CAS

One possible use of CAS is to di-agnose children with attention def-icit disorder (ADD). Such childrenshould score lower in attentionthan in planning or simultaneousand successive processing. Table 1shows the CAS scores of 2 boyswho had been diagnosed withADD. The scores show the pre-dicted pattern, confirming the orig-inal diagnosis.

A second example of clinicalusefulness of CAS is provided by a12-year-old American boy whosustained a closed head injurywhen he hit the dashboard of amoving car (Naglieri & Das, 1997).He was referred for treatment be-cause of behavior control problemsand poor grades in school. His IQscores fell within the normal range,between 112 and 98. In contrast, hisCAS scores were as follows: Plan-ning, 73; Attention, 79; Simulta-neous, 100; and Successive, 110.These scores clearly show the pro-

file for a deficit in planning and at-tention-arousal.

The CAS has been used in sev-eral countr ies , inc luding theUnited States, and has aided in thediagnosis of cognitive deficits (seeTable 2). None of the individualswhose scores are reported in Table2 had a below-average full-scale IQscore, but their CAS scores showclear deficits in particular cognitivecomponents. These results supportthe position that a general view ofintelligence is of little value in ob-taining the cognitive profiles inthese cases. Obviously, a single IQscore by definition does not pro-vide a profile; as a consequence, in-dividuals with cognitive deficitswill often not be identified by IQmeasures and will not benefit fromthe diagnosis that would be af-forded by multidimensional sys-tems of cognitive assessment.

APPLICATION TOREADING DISABILITY

Does the source of dyslexia lie incognitive skills needed only inreading-related tasks (i.e., in proxi-mal processes), or does it lie in amore fundamental process identifi-



ers), or are both slow and inaccu-rate. In contrast, individuals whoare generally poor readers mayhave low Successive scores, likedyslexics, but unlike dyslexics canhave lower than average scores onthe three other PASS measures.They make phonological errors andare slow decoders. But unlike dys-lexics, they show difficulties in com-prehension of syntax and meaning.

New research using brain-neu-roimaging techniques continu-ously advances researchers’ knowl-edge of cognitive processes, such asreading. For example, a recent study(Pugh et al., 2000) demonstrated thaton reading tasks that required pho-nological processing, such as de-termining if two made-up wordsrhyme, normal readers showed ro-bust connectivity between the an-gular gyrus and other areas in theback of the left hemisphere, whereasdyslexics did not. However, nor-mal readers and dyslexics showedsimilar connectivity between theseareas on reading tasks that did notdemand phonological processing.Such research implies that support-ing neural connections that are in-tact can be utilized by dyslexics ifactive phonological exercises arenot demanded of them. Appropriateremediation or intervention pro-grams, such as PREP, that do notteach phonics and do not requireoral reading, but still enhance suc-cessive processing, can be effectivein helping dyslexics become betterreaders. If such programs are insti-tuted during the developmental pe-riod, true dyslexics can also makeuse of compensatory mechanismsavailable through the posteriorparts of the right hemisphere.

APPLICATION TOMENTAL RETARDATION:

DOWN SYNDROME

CAS has also been used to inves-tigate the deficits of individuals

with mental handicaps of variousetiologies. A comparison of indi-viduals with Down syndrome (DS)and individuals who have mentalretardation but not DS showed thatDS is associated with a broad defi-cit in successive processing. Indi-viduals with DS have weak serialrecall of spoken words, and it istherefore suspected that DS islinked to a deficit in phonologicalmemory. Further, CAS tasks showthat age-related decline in attentionand successive processing is fasterin individuals with DS than inthose without DS. The majority ofindividuals with DS develop de-mentia after age 50 and performvery poorly on all CAS tasks com-pared with mentally handicappedindividuals who do not have DS(Das, Divis, Alexander, Parrila, &Naglieri, 1995).

DIRECTIONS FORFUTURE RESEARCH

What might be some usefulleads for further research? Each ofthe four processes represented inthe PASS model requires furtherinvestigation. For example, succes-sive processing contributes to un-derstanding printed words andcomprehending syntax. But at amore specific level, can the modelilluminate the difference betweenreading disabilities associated witha slow rate of word reading andthose characterized by a high rateof phonological errors? Poor read-ers who are slow but not inaccurateshould do poorly on the CAS suc-cessive-processing test that de-mands articulation, Speech Rate.This test requires rapid repetitionof two or three simple words 10times. Slow-but-accurate readersshould not perform poorly onother successive-processing tests(e.g., serial recall of words and sen-tences) that do not demand fast ar-ticulation. In contrast, people who

are both slow and inaccurate read-ers should do poorly on all succes-sive-processing tests. This predic-tion is yet to be investigated, but ifit is in fact correct, is a deficit insuccessive processing still a usefulexplanation for the slow-but-accu-rate type of reading disability? Per-haps while reading they not onlytake longer to decode words, a taskthat engages successive processing,but also take a longer time to disen-gage attention from one word tothe next, which slows down read-ing. This possibility can be testedwith a naming-time task in whichthe test taker is required to read aseries of familiar words rapidly. Isthe slow-but-inaccurate readerpoor in both speech-rate and nam-ing-time tasks?

Another promising path for fu-ture research concerns the concep-tualization of planning and its rela-tion to efficiency in languagerepresentation. Planning is seen inregulation of behavior achievedthrough the use of language. Atyp-ical individuals, such as those withDS (see the previous discussion) orpeople with congenital hearing loss(as opposed to acquired hearingloss), should be relatively weak inplanning complex activities to theextent that language plays a role insuch planning. Studies examininghow they plan and how their abil-ity to plan can be augmented holdpromise for testing the connectionbetween planning and language.

Recommended Reading

Das, J.P., Kar, B.C., & Parrila, R.K.(1996). (See References)

Das, J.P., Naglieri, J.A., & Kirby, J.R.(1994). (See References)

Luria, A.R. (1966). (See References)

Acknowledgments—

This article reflectsthe ideas and writings of several collabo-rators, including R.F. Jarman, J.R. Kirby,J.A. Naglieri, T. Papadopoulos, and R.K.Parrila.



Note

1. Address correspondence to J.P.Das, Developmental Disabilities Centre,6-123 D Education North, University ofAlberta, Edmonton, Alberta, CanadaT6G 2G5; e-mail: [email protected].

References

Das, J.P. (1999).

PREP: PASS Reading EnhancementProgram

. Deal, NJ: Sarka Educational Resources.Das, J.P., Divis, B., Alexander, J., Parrila, R.K., & Na-

glieri, J.A. (1995). Cognitive decline due to agingamong persons with Down Syndrome.

Researchin Developmental Disabilities

,

16

, 461–478.

Das, J.P., Kar, B.C., & Parrila, R.K. (1996).

Cognitiveplanning

. Thousand Oaks, CA: Sage.

Das, J.P., Kirby, J.R., & Jarman, R.F. (1975). Simul-taneous and successive syntheses: An alterna-tive model for cognitive abilities.

PsychologicalBulletin

,

82

, 87–103.

Das, J.P., Naglieri, J.A., & Kirby, J.R. (1994).

Assess-ment of cognitive processes: The PASS theory of in-telligence

. Boston: Allyn and Bacon.

Donald, M. (1991).

Origins of the modern mind

.Cambridge, MA: Harvard University Press.

Frith, C.D. (1997). Linking brain and behavior. InR.S.J. Frackowiak, K.J. Friston, R.J. Dolan, &J.C. Mazziotta (Eds.),

Human brain function

(pp.3–23). San Diego: Academic Press.

Gardner, H. (1983).

Frames of mind: The theory ofmultiple intelligences

. New York: Basic Books.

Luria, A.R. (1966).

Human brain and psychologicalprocesses

. New York: Harper and Row.

Naglieri, J.A., & Das, J.P. (1997).

Das-Naglieri Cog-nitive Assessment System

. Itasca, IL: RiversidePublishing.

Posner, I. (1993).

Foundations of cognitive science

.Cambridge, MA: MIT Press.

Pugh, K.R., Mencl, W.E., Shaywitz, B.A., Ful-bright, R.K., Constable, R.T., Skudlarski, P.,Marchione, K.E., Jenner, A.R., Fletcher, J.M.,Liberman, A.M., Shankweiler, D.P., Katz, L.,Lacadie, C., & Gore, J.C. (2000). The angulargyrus in developmental dyslexia: Task-specificdifferences in functional connectivity withinposterior cortex.

Psychological Science

,

11

, 51–56.Sternberg, R.J. (1985).

Beyond IQ: A triarchic theoryof human intelligence

. Cambridge, England:Cambridge University Press.

Wagner, R.K., & Torgesen, J.K. (1987). The natureof phonological processing and its causal rolein the acquisition of reading skills.

Psychologi-cal Bulletin

,

101

, 192–212.

Abstract

Diverse lines of researchsuggest that schizophrenia is agenetically influenced neuro-developmental disorder. Fam-ily, twin, and adoption studiessuggest that most cases ofschizophrenia involve a geneticdiathesis that is necessary butnot sufficient for developmentof the disorder. Histological,neuroimaging, and neuropsy-chological findings converge inproviding evidence for medial-temporal and frontal lobe dys-function that likely predates theonset of psychosis. Behavioralphenomenology and neurobiol-ogy suggest that dopamineplays a crucial moderating rolebetween these structural abnor-malities and functional impair-ment. Recently, investigatorshave used animal models andclinical syndromes to integratethese findings into neurodevel-opmental models of schizophre-nia that hold great potential foryielding etiological insight.

Keywords

schizophrenia; neurodevelop-ment; etiology; predisposition

The past decade has seen a pro-liferation of research findings inthe field of schizophrenia, withprovocative developments in mo-lecular genetics, neurobiology,neuroimaging, neuropsychology,and studies of high-risk individu-als . Although the et iology ofschizophrenia remains enigmatic,scientists are gaining ground in de-veloping plausible models of vul-nerability to this disorder. In thepast, most research findings haveprovided insights into selected as-pects of the disorder without yield-ing a comprehensive theory thathas received broad-based ap-proval. Recently emerging neuro-developmental models of schizo-phrenia, however, are capable ofaccommodating diverse findingsand are receiving widespread sup-port among schizophrenia investi-gators.

Neurodevelopmental modelspropose that vulnerability to schizo-phrenia results from a disruption inforebrain development during theperinatal period. A brain lesion thatoccurs early in development is hy-pothesized to lie dormant until nor-mal brain maturational events trig-ger the appearance of traditionaldiagnostic signs, typically in adoles-cence or early adulthood (Wein-berger, 1987). Such models are sup-ported by reports of increasedintrauterine and perinatal complica-tions among individuals withschizophrenia, as well as by demon-strations that neurological, neuro-psychological, and physical abnor-mali t ies predate the onset ofpsychosis. Although this evidenceis far from conclusive, neurodevel-opmental models hold immensepromise as a heuristic for bridgingresearch in multiple domains andposing questions central to discov-ering the etiology of this disorder.

GENETIC AND ENVIRONMENTAL VULNERABILITY

Well-replicated findings fromfamily, twin, and adoption studiesindicate that there is a substantialgenetic component to the predispo-sition for schizophrenia. The likeli-

Schizophrenia: A Neurodevelopmental Perspective

Heather M. Conklin and William G. Iacono

1

Department of Psychology, University of Minnesota, Minneapolis, Minnesota

A Better Look at Intelligence

Documents

Transcript of A Better Look at Intelligence