Eye Movements and Inspection of Integrated Circuit Chips (ICC)

PsychophysiologicalApproaches to Human Information Processing F. Klix, R. Naatben, and K. Zimmer (Editors) 0 Elsevier Science Publishers B.V. (North-Holland), 1985

37 1

EYE MOVDENTS AND INSPIXTION OF l"EGRATED C I E U I T CHIPS (102)

Ch. F. Schmidt Section of Occupational Sciences D e p a r m t of Psychology Technical University Dresden Dresden

GDR

Recordings of eye w m t s provide valuable data f o r validating psychological and mathematical models which have been put forward t o describe visual search behavior, information processing and action control. The r e s u l t s of three experiments are presented. These are aired t o give a b e t t e r understanding and improvement of visual inspection i n general and of different types of integrated c i r c u i t chips i n particular. T m modes of reprocessing w i t h respect t o s m conditions of influence are discussed. INTFODUCTION

Recordings of eye marements provide valuable data f o r validating psychological and mathematical d e l s which have been put forward t o describe visual search behaviour, information processing and action control. S m of these models have proved useful i n predicting search and inspection performance with hidden targets. I n contrast t o pure laboratory tasks and models derived f r m a theoretical point of view we tried t o find out, whether the several shortccmings concerning the nonlinear functions i n ccanplex search processes are d e p d e n t on the stimulus material o r on the subjects. This idea is not surprising because of the limited application of the search mdels. They use d i s c r e t e t a r g e t s on a rel a t i v e l y hamogeneous background, as opposed t o such inspection requiremnts consisting of frequently poorly defined tarqets on non-hamogeneous and varying background. W e conclude: k n m l d g e sources apply simultaneously and our perception is the product of the simultaneous interactions among a l l of them. This principle of the doubled determination of the eye m e r e n t s w a s suggested by Gippenreiter (1975). Klix (1979) sumnarized these f a c t s with the statement that the structure and disposition of the memory is determined by the organization of the perception. These are the

312

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reasons why we w i l l try t o bridge the gap betwen w l l explored laboratory tasks and industrial inspections by mans of the organizing, regulatian and action orienting function of eye m e m t s . Eye menents and their paramters are regarded in t h i s context as indices of organizational processes in perception. METHOD

Nine w e l l trained and skilled femals inspectors were seated i n front of a screen and a teletype. They had to look for ten, twent y or t h i r t y one f a u l t s or quality deviations hidden i n three different types of integrated circuit chips (ICCS) each occuring 130 times. The different selected ICCs consisted of three mnditions and the structural information content (SI) has been calculated by means of a measurement, paposed by Lee-g (1969) and Van T u i j l (1980) (6.Figure 2). The different faulty or correct ICCs have been selected from 192.ooO photographs and were recorded with the aid of a VR 580 S Color cassett-recorder. The screen subtended 16O vertically and 18O horizontdly to an inspect o r s eye, which is m t less than the 200 the visual f i e l d subterded in a microscope. The maximum search-& for 130 screen-projections t o be called by the operator was to 200 minutes. The inspector gave his decisions about f a u l t s or deviations i m d i a t e l y into the teletype w e l l familiar t o the input wnditions. Eye mwerrwt parawters were recorded using the Psychological-Apparatus-Fa. Takai & Co.Ltd. 1971 supplemnted and adapted by a oanputer system PAI 1001 (cf. Figure 1 ) .

As dependent variables the follawing were recorded: Number of fixations i n the functional visual f i e l d , fixation tines, number of horizontal saccades, number of v e r t i c a l saccades, saccadic onset-delay (Vaughan 1982), nof refixations and inspection time, f a u l t conspicuity and correctness of f a u l t conspicuity

.

The f u l l cycle of data processing was assessed by analyses of variance and regression analysis using a level of significance cx= 0.01 throughout. In this paper we confine ourselves t o the eye mement variables. FESULTS

1. Increasing SI was connected with an increas in the density of the non-hamgeneous background and r e s u l t s in an increase of man fixation tim, and consequently i n an increase of man f a u l t conspicuity search time ( 6 .Figure 2). This finding

Inspection of Integrated Cirnrit sips

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Figure 1

Schematic representation of eye nwveirent measurenrent by the a i d of an apparatus, produced by Takia & Co.Ltd. supplemented and adapted by a f u l l cycle data processing W u t e r system TPM 1001 (rodified by Rashbass 1980).

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Designation Infrared luminescence Television Camras Tapes storages Electroencephalograph fill cycle data processing system TPAI 1001 Results calculated and printed Subject (Inspector) Screen Video recording system Teletype input H e a d holding device

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Figure 2 Mean fixation time as an exponential function of the nunher

of errors stored under conditions of 1st: It32 Hanogeneous background 2nd: ICC N~-hcmogeneous background ( s-le 1 3rd: ICX - Non-hamgeneow background (amplicated) (Ss = 9)

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w a s independent of the w e l l stored m r y set s i z e of f a u l t s or deviations to be found cut. An increase of mean fixation tzhm s h a d , w i t h i n the c o d t i a n s , a multiple exponential regressim with significant positive slope (p < 0.01). 2.

Interaction effects betwen calculated SI and m r y set s i z e proved t o be significant. There were highly significant differences (p < O.CO1) during a l l three conditions w i t h i n and betwen SI as w e l l as w i t k i n and between the consistent internal representations searched for. Th= mre ccmplicated the non-hawgeneous context of the stimlus density, the higher the man fixation th (cf. Figure 2 ) .

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3. Besides the increase of the man fixation time d e m s on the

context configurations, the number of fixations necessary t o find out the relevant targets increased too (cf. Figure 3 ) .

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number of fixations dependent on m.mry set s i z e (errors stored) and background differences (conditions

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A logarithmic transformation of the multiple regression w i t h i n one m r y set s i z e reveals linear slopes not differen-

tiated i n their slope coefficients, although the starting point conditions are different in level. The nmker of fixations varied in dependence on the number of internally stored representations and on the SI betwen 16 and 102. It can be seen that a l l distances dependent on the conditions are significant (p < 0.01). This r e s u l t also proved true for a l l the interaction effects calculated.

4. The man delay of saccadic onset increased w i t h the n-r of targets stored and w i t h increasing SI from 160 to 370ms. Figure 4 d m n s t r a t e s t h a t multiple exponential regressions, w e effected both between different SI and inspected gaze

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Figure 4 Mean n m b r of refixations aependent on m e m ~ l l yset s i z e and background differences (condition 1 - 3 ) (SS = 9).

of the field. All points of the regressions are significant without any exception (p < 0.01). A linear regression was calculated bethe increasing m r y set s i z e s . 5. The mean n m h r of refixations supports the r e s u l t s presented, i n the direction expected (cf. Figure 5 ) . Dependent on the S (especially considering the m r y set s i z e varying fran $0 t o 31 a significant slope could be confirmed (p < 0.01). The same trend can be seen regarding the SIvariation fran 2 t o 3. An m n t i a l regression was found. These points t o a rising capacity l i m i t of the sensory storage, as w i t h the context control, that can not be counter-

balanced.

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Figure 5 Mean saccadic delay time as a function of background under conditions of the m r y set s i z e (error stored) (SS = 9 ) .

6. "he percentage of horizontal saccades diminished in the 'saane degree as SI increased (p < 0.01 1 Figure 6 shuws this lapse

.

of the horizontal saccades. A diminution of the horizontal saccades fran 92 % t o 68 % w a s found. W i t h i n the SI-amfiguraticms the diminution is not significant under condition 1 (p < 0.05). The horizontal scanning rate is obviously cut down i f the mtext conditions are w e l l structured and the subject is familiar with the sensory input.

DISCUSSION The presented eye mement analyses gives scme idea of the effectiveness of regulation of sensory infonration storage. Fefixatio m , inhibitions of reproductions, saccadic onset-delay time and the increase of the fixation time are e s s e n t i d l y s i p of i n f a mtim preprocessing phases w i t h i n periods of critical stimulus lapse. Sensory units already created were erased where there was

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Percentage of horizontal saccades i n ccmparism with v e r t i c a l ones under conditions of the quasi-experirent i n visual inspection of integrated circuit chips. (Ss = 9 ) .

discontinued uptake of non-harogeneous context stbuli. For t h i s purpose the &el of information preprocessing published by Schneider & Shiffrin (1977) is used t o give a theoretical approach t o cur findings. It seems t o be useful t o take i n t o account four points of view (see Table 1) : 1. The control of visual search processes depends on both the orientation function provoked by externdl stimuli and the regulative function of consistent interndl representations. This double - interulediate mode of informatian proprocessing allwes us t o cane t o terms in msdifying autanatic versus con-

trolled information processing.

mxTement paramters reflect scanning procedures which habituate and continually repeat. Obviously i n autanatic information preprocessing, saccades and fixation tirnes are preProgrd.

2. The eye

1m

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Inspection of Integrated Circuit Chips I

D E O ~ I o N

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PREPFUXESSING

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set s i z e consistent or varvina. Internal representatl&.are stable Gt flexible internal representations are necessary to search for features, Determinants are ambiguous (fuzzy features)

m r y set s i z e consistent,

Memory

Internal representations are stable, Determinants are unambiguous

CakuhDifferences beted structural i n f o m t i o n of the target-contextdifferences are smaller than 2 and relatively

Differences between calculated SI are varying and greater than 3. E l m t s of the targets are similar t o elerrwts of the context or hidden in non-harogeneous background.

Preprogranmed eye rrwements proprograrm-ed saccades, Fixation t i n e is relatively constant, N u n h e r of fixations relatively ccmstant , Scanning path habituated and always reapeating, Interf ixation distances are prolonged, D i r e c tion of eye m m t s horizmtal

Anticipated eye rmxrements Anticipated and dalyed Saccades, Fixation tinV2s vary greatly, N u ~ k e xof fixations varying, hardly diminishing, Scanning path is not always the saw, Interfixation distances are shortened, Direction of eye mmts horizontal as wll as vertical

Table 1

Two mdes of information preprooessing i n visual search and inspection, ccPnpleting the d e l of Schneider

&

Shiffrin.

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3. Controlled preprocessing procedures are necessary i n s a ~ cases for instance m d i t i o n s of n o n - h q e n e o u s context and varying s t h l i . Besides consistent internal representations, a flexible u t i l i z a t i o n of characteristic marks is required. This access t o f l e x i b l e and cognitively regulated control representations can be damnstrated exactly by a cognitive feedback lccp i n t d i a t e d by eye merrents. 4. The infarmation preproessing phases can be distinguished amceptually, and empirically. As previously m n f M this s u p

lies us w i t h additional kncwledge of how perception does work. A rapid change between autanatic and a m t r o l l e d information is ass&.

( 1 ) G i p p e n r e i t e r , J.I., Z u r Funktion der Augenbewgungst2itigk e i t urd ihre Erforschung, in: Lmcw, B.F. and Vergiles, N.J. (eds.), Wtorische Karponenten des Sehens (Deutscher verlag der Wissenschaften, Berlin, 1979). ( 2 ) K l i x , F., Introduction, in: Ueckert, H. atid Rhenius, D. (eds.1, Kanplexe m s c h l i c h s Informationsverarbeitung (Huber, Bern, 1979). (3) Leemenberg, J.L., (Den Haag, 1969).

Structural Informtion of visual pattern

Interindividual differences of p e r f o m c e i n the recognition of geatletrical patterns, Paper presented a t the XXIII. Int. Ccngress of IUPsyS ( k i p z i g , 1980, un-

( 4 ) Schmidt, Ch. F.,

publ.)

.

(5) van T u i j l , H.F.J., Perceptual interpretation of c~nplexline patterns, J. of Ekp. Psychol. HPP 6 (1980) 197-221. (6) Vaughan, J., Control of fixation duration in visual search and merrory search. mother look. J. of Exp. Psychol. HPP 8 (1982) 709-723.