256 LOW. GRONBURG. A1\D SHERLING

addit ion to the mediator necessary to r solutio n of the iud ividu alproblems. a co mmo n mediat or such as "t he new one" wasut ilized by that gro up.

The difference between the ty pe of learn ing set fo r thekindergartn ers and first graders compares with the d ist inctionmade by Reese (19 63) between learning sets and performan cesets: Per formance sets are a generalized learning-to-learn whereaslearn ing sets invo lve the acq uisition of solut ions commo n to anumber o f problem s The present findi ngs that imp rovement inperformance over prob lems was not int1uenced by the order ofoccurr ence of the par tic ular prob lems lend s support to the viewthat the first grad ers were acq uir ing a learn ing set.

Th e present results suggest that learn ing sets for simpleconcepts could provide a useful mechanism for the st udy ofage-related mediat ing mechani sms. The specifi c reversal taskproved simple for the first grad ers as evidence by the ceilingeffect on RT. The presence of new irrelevant dimensi o ns duringthe rever sal shifts or the use of other int radi mensional shift s asdes cribed by Wolff (1967) might pro vide a mor e sensit ive indexof age differen ces.

REFERENCESBrown , A. JJ., & Scott, M. S. Transfer between oddity and

Bulletin of the Psy chonomic Society19 75, Vol. 5 (3); 256-258

relat ive size co ncept s : r eve rsa l a nd e xt rad im ensio n al shifts .J ournal of E xp er im ental Child Psych o log y , 1972, 1 3 ,3 50 -367 .

Goss , A. E . Verba l m ed iating res po n ses and co ncept fo rmation .Ps ycho logical Re vie w, 19 6 1 , 68 , 248 -274 .

Kendler, H. H .. & Ke ndler, T . S . Vertical and hori zontalprocesses in pro b lem solving. Ps ycholo gical Review , 1962, 69 ,1-16 .

Kendler, T . S . An ontogeny of mediatio nal d e fici en c y . ChildDe velo p rn ent , 19 7 2, 43, 1-1 7 .

Kendler. T . S . , & Kend ler , H. H. R eversal and nonreversa l shiftsin k inderg arten ch ild r en . Journal o f Exp er imental Psy ch ol ogy ,19 59,58 , 5 6·60 .

Kendler, T. S., Kendler, H. H .. & Wells, D . R e versal a ndnonreversal shifts in nurser y schoo I child re n. J ournal o fCo m parative a nd Physiological Psycholog y, 1960, 53, 83-88.

Reese, H . W. Discrimination learning se t in ch ildren . In L. P.Lip sitt and C. C. Spiker (E ds .L , Advances in childdeve lo p men t and behavior, Vol. I , New Yo rk : AcademicPress. 1963.

Savaro, A., & Kolodny, M. Learning set and shift b ehavior inch ildren . Journal of Experimental Child Psycholog y , 1969, 7 ,21·30.

Wolff, J. L. Concept-shift and discr imination·reve rsallearning inhumans. Psychological Bulletin, 1967,68,369-408.

(Recei ved for publication November 20, 1974.)

. Memory search as a function of phonological context

ROBERT B. DICK and LARRY HOCHHAUSOklahoma State University, Stillwa ter. Oklahoma 74074

The 11 subjects memorized variable lists of either one or three spoken consonant-vowel (CV)syllables. Each list (positive set ) was followed by a spoken CV test syllable and subject 's task was toindicate whether or not the test syllable matched a syllable from the list. Negative test probes wereeither phonemically distinct from items in the list or were phonemically similar to list items. Reactiontime (RT ) increased with list length and RT was faster to positive than to negative probes. Additionally,a significantly faster memory scanning rate was ob served for phonemically distinct negative probes(53 msec/item) than for negative test probes which were similar to items in the po sitive set(81 msec /item). Contrary to earlier research it was concluded that phonological dist inctive features havea large effect on memory search RT.

Analysis of distin ctive features of stimulus displayshas occupied several researchers in recent years. Gibson 's(1969) recently prop osed th eory of perceptual learninghypothesized that differen tiation in visual displaysinvolves the searching and processing of th e distin ctive

The research for this paper was su p ported b y Oklahoma StateUniversi t y resea r ch funds. This p aper is sponsored b y Robert F .Stanners who t ak es fu ll editorial responsibility for it .

R obert Dick is now at Na ti ona l Institute of Mental Health,R egional Office IV, Atlanta , Ge orgia .

R equests for reprints should be addressed t o Larry Hochhaus,Department o f Ps ycholo gy, Oklahoma State University,Stillwa ter, Oklahoma 74074.

features present. Employing a disjunctive reaction timetask, Yonas and Gibson (1967) foun d tha t a visualdistinctive feat ure (diagonality) commo n to all positiveset items produced greate r reduction in latencies withpractice than was found when the diagona lity featurewas present in both positive set and negat ive set items.

The auditory analog and histo rical basis of Gibson 'svisual distin ctive features is the phonemic dist inctivefeature. Accord ing to Jak obson , Fant , and Halle (1967),anyone language code has a finite set of dist inctivefeat ures and a finit e set of rules for grouping these

256

MEMORY SEARCH AND PHONOLOGICAL CONTEXT 257

features into phonemes. In an auditory Sternberg-typetask, Foss and Dowell (1971) failed to replicate theresults of Yonas and Gibson; similar positive setphonemes did not decrease memory search reaction time(RT) relative to the condition of dissimilar positive setphonemes.

While presentation mode and task differences mightaccount for the failure to replicate, at least twoadditional factors may have contributed to Foss andDowell's negative results. First , regarding experimentalmaterials, similar and dissimilar phonemes were notsystematically chosen and, second, the phonemes to berecognized were each presented as the initial phoneme ofa word . Perhaps the presence of other phonemes made itdifficult for subjects to scan memory on the basis of theinitial phoneme's distinctive features.

To accommodate these criticisms , phonemic materialsin the present experiment were systematically chosenfrom Brown's three-dimensional distinctive featurematrix (Brown, 1965). Also, phonemes in the presenttask were presented as spoken consonant-vowel (CY)syllables; the vowels in each syllable were a constant[-0] sound .

Additionally, to more precisely demonstrate thesubject's use of distinctive features in short-termmemory search, the conditions of phonemic similarityand dissimilarity were drastically altered in the presenttask . Instead of manipulating the distinctive featuresimilarity of positive set items (as did Foss & Dowell,1971), the present procedures manipulated the similaritybetween negative probes and the positive set items(which were homogeneous with respect to intrasetsimilarity). The present design is most like that ofNeisser (1964) who, in a visual search task, found thatsimilarity between target and nontarget items had a largeeffect on the visual scanning rate. For example, Neisserfound that the letter Z was identified faster in thecontext of letters with rounded lines than in the contextof a straight line letters. For the present experiment itwas hypothesized that RT is faster for "far" negativeprobes (those phonemically distinct from positive setsyllables) than for "near" negative probes (probes similarto positive set items).

METHOD

SubjectsThe subjects were II Oklahoma State University

undergraduates recruited voluntarily from undergraduatepsychology sources . Each subject was tested in a single session of144 trials preceded by 12 practice trials. The single session lastedabout I h with a 5-min break at the halfway point.

Stimulus MaterialsBrown's (1965) distinctive features matrix for eight

consonants was used to construct the stimulus lists. The vowel(-0 I was added to each consonant, and lists of one and threeCV syllables were recorded on tape for presentation to theSUbjects. Probes were also CV syllables, with the positive probe a

member of a previously presented 'list , or set, and a negativeprobe not a member of the previously presented set. Negativeprobes were also chose according to a " near" and "far"distinction based on the features of the matrix . For set size 3, a"near" negative probe had two features in common with oneitem in the memory set and one feature in common with theother two items in the memory set. A "far" probe had onefeature in common with two items in the memory set and nofeatures in common with two items in the memory set and nofeatures in common with the third item in the set. In Set Size I ,a "near" probe had two features in common with the singlememory item and a "far" probe had no features in common withthe single memory item. The CV syllables used were Ibol, Ipol,lvo], lio], Idol, [io], 100/, and I~o/.

ProcedureStimulus materials were presented auditorily on a Realistic

tape recorder over headphones. The left channel of the stereorecorder was used to record the memory sets and probes forpresentation to the subjects. Probes were simultaneouslyrecorded in the right channel and this channel was used toactivate a voice key which started a Hunter Klockounter.Simultaneous recording of the probes in both channels resultedin the voice key (Gerbrands) firing the Klockounter at the sametime the subject heard the probe stimulus. The Klockounterstopped when the subjects made their response to the probe bymoving a two-way toggle switch mounted on a table in front ofthem to either a yes or a no position. Reaction time inmilliseconds was recorded from the Klockounter, and posit iveand negative responses were counterbalanced with the left andright toggle switch responses. Each trial was initiated by theword "ready," followed 2 sec later by the meory set (one orthree consonant-vowel syllables). A 5-sec pause occurred beforethe probe item was presented. Items in the memory set werespaced at I-sec intervals , and there was a 10-sec interval betweeneach trial.

Subjects were presented with 144 trials arranged into two trialblocks . There was a 5-min rest period between each block and 12practice trials preceded the experimental trials. One half of thetrials involved Set Size 3 and half were of Set Size I . There werean equal number of positive and negative probes, and one half ofthe negative probes were "near" .negative and one half were"far" negative. In the positive Set Size 3, the one, two, and threepositions were probed eight times each. Each trial consisted of amemory set (one or three items) and a probe (positive ornegative) . Trials were randomly arranged for presentation to thesubjects.

RESULTS

Mean reaction times were calculated for each subjectwithin each category. No block differences wereindicated, so the data were collapsed across blocks forsubsequent analysis. A completely within-subjectstwo-factor ANOYA indicated significant differences inscanning rate between probe type (F = 12.08 df= 1/10,p<.Ol) and set size (F = 17.16, df= 1110, p< .Ol).Significant interactions occurred between Subjects byProbe Type (F = 5.01, df= 1/10, p < .01). There was nosignificant interaction between probe type and set size,indicating minimal slope differences. Regression analysison the same data indicated a scanning rate of about71 msec per item using the positive probe and 67 msecper item with the negative probe .

Further analysis of the negative probe items revealed

~58 DICK AND HOCHHAUS

Table IMean Reaction Time and Error Rates for Each Condition Over All Trials

----------- - - - -Set Size I Set Size 3-_._--- ---

Probe Type Positive Negative Positive Negative

Combined Ncar Far Combined Near Far

Mean RT .5 21 .596 .6 19 .592 .R06 .865 .94 1 .805Number of Errors 21 7 6 I 58 44 36 8Percent Error 5 .3 1.8 3.0 .5 14.6 ILl 18.2 4.0

the most interesting results. With no block differences,scores on negative probes were totaled and averaged overall trials according to set size and the near-farclassification giving a mean reaction time for eachsubject. A matched-groups t test supported thedistinctive features hypothesis in Set Size 3 showinggreater search times for the near negative probes (t =1.31, df = 10, p < .0 1). Set Size 1 differences were notsignificant (t = 1.31, df =10, P < .30) . The least-squaresequation on the same data revealed a scanning rate of81 msec per item for the near negative probe and53 msec per item for the far negative probes (SeeFigure I) .

A second analysis of variance was performed on thesubjects' mean RTs to the positive probe (serial positionand subjects were the two factors) and revealed asignificant serial position effect, with the faster RTsoccurring in positions one and three and slower RTs inposition two (F = 4.14, df = 2/18 , p < .05). ANewman-Keuls test further substantiated the significanceof both a primacy and a recency effect in the serialposition data. Table 1 presents a summa ry of the errordata and mean reaction times for all subjects in eachcondition over all trials . Examination of the errortabulations reveals the highest error rates occurred in setsize three with the positive and negative probes.

DISCUSSION

The results clearly indicate the impo rtance of stimuluscontext in memory scanning . Items which are more phoneticallydistinct from other items are more quickly identified. This viewis supported by the significant difference ob tained in Set Size 3,where the far probe (maximum of one distinctive featureoverlap) produced faster reaction time than the near probe (twodistinctive features overlap). Failure to obtain significance in SetSize I co uld probably be attributed to size of the memory set,which may have limited the advantage of using distinctivefeatures. With more distinctive feature overlap, there is moreconfusability in processing the items. However , when only oneitem is being scanned the effect is limited.

Overall, the scanning rates for the positive and negative probeswere approximately equal (71 and 67 msec/item), but when thenegative probe was analyzed according to the underlyingdistinctive features. marked differences occur. The near negativeprobes (81 msec /itern) are slower than the far negative probes(53 msec/itern). The data clearly indicate that the short-termmemory scanning rate can be affected by the stimulus context.

These results do differ from the previous study by Foss andDowell (1971) which used phonemic distinctive features in a

Sternberg (1969) type task . The main differences between thestudies were referred to in the introduct ion and included use inthe present study of consonant-vowel similarity to the negativeset instead of the positive set , and the use of Brown's dist inctivefeatures matrix which appears more concise than the systemused in the Foss and Dowell study . Additionally examination ofthe subject's error data reveals a possib le explanation for thediscrepancy in results (see Table I). The subjects in thisexperiment had th eir highest error rates in Set Size 3 with thepositive and near negative probes (14 .6% and 18.2%) indicatingthe level of acoustic confusability was very high . It could be thatwith too much distinctive feature over lap, the level of acoust icconfusability is so high that SUbjects perform close to chance onsome items. In most cases, operating at the chance level on theseitems should increase the scanning rate for the items . Thereduced scanning rate and error rates with the far negativeprobes, were the distinctive feat ures overlap is minimal, seems tosupport this notion. Previous research has shown error ratesaffected by acoustic confusability in short-term memory(Wicklegren , (965).

The results in the present study support a recent study byLyons and Briggs (1971) who manipulated the context of thestimulus material presented and accuracy of response. Theyfound the intercept varied with the accuracy levels while theslopes varied with the stimulus material. Examination ofFigure I of the present repo rt shows the relative closeness of theintercepts for the negative response, but a subsequent divergenceas the material is scanned (the difference between scanning oneand three items.),

REFERENCESBrown, R . Socia l psychology. New York : Free Press, 1965.Burrows, D. , & Okada, R . Serial position effects in high-speed

memory search. Perception & Psychophysics, 1971, 10,305-308.

Foss, D . J ., & Dowell, B. E . High-speed m ••mory ret rieval withauditorily presented stimuli. Percepriou & Psychophysics.1971.9,465-468.

Gibson, E. J. Principles o f pe rceptual learning and development.New York: Applet o n-Oentury-Crofts , 1969.

Jakobsen, R., Fa nt, C. G. M.. & Halle. M. Prdimina!'ies to speechanalysis: The distinctive fea tures and their corre late•.Cambr id ge. Mass : The M.•J..J:.Xr_e_s_~. )J}~.7..

Lyons, J. J., & Br iggs. G. E . Speed-accuracy trade-o ff withdifferent types of stimuli. Journal of ExperimentalPsychology, 1971.91,11 5-119 .

Neisser, U. Visual search . Scientific American, 1964. 210,94-102 .

Sternberg, S . Memory-scanning: Mental processes revealed byreaction-time experiments. American Scientist, 1969, 57,421-457 .

Yonas, A. & Gibson, E . J . A developmental study of featureprocessing strategies in letter discrimination. Paper presentedat the meeting of the Eastern Psychological Association,Bost o n . April 1967 .

Wickelgren, W. A. Dist rin ct ive feat ures and errors in short-termme mory for English words. Journal of the Acoustical Societyo f America. 1965. 38, 583-588.

(Received for publication November 13, 1974.)