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Study-time of sentences as a function of their specificity and of semantic exploration
Acta Psychologica 37 (1973) 43 -5 3.0 North-Holland Publishing Company
STUDY-TIME
OF SENTENCES AS A FUNCTION OF THEIR
SPECIFICITY AND OF SEMANTIC EXPLORATION Jean-Fraqois
LE NY, Guy DENHIkRE
and Danielle LE TAILLANTER*
University of Paris 8, France Accepted October 20, 1972
In self-paced learning conditions the study-time of sentences is supposed to depend jointly upon the informative content of the material and upon its exploration by the subject in the course of learning. In exp. 1 informative content was varied by using sentences constituted either of general or of specific words; study-time was found to be significantly longer for the latter sentences than for the former and the recall performance to be equal. Differential semantic exploration and storage were instigated by presenting in the series either pairs of similar, and thereby contrasted sentences, or isolated sentences. In exp. 2, study-time of the former sentences was longer than that of the latter; but the first recall performance recorded with the contrasted sentences was also higher. The divergent effects of the nature of the material and of the activity of the subject upon study-time and recall performance were emphasized.
It has been previously shown in several experiments that Ss placed in a self-paced learning situation regulate their study-time (ST) according to the difficulty of the different parts of the material. Factors exerting an influence upon the number of repetitions necessary to learn an item in conventional situations, or upon the number of errors after a fixed amount of time devoted to learning, also have an effect upon self-paced ST. For instance, in self-paced serial learning, an inverted-U curve was found to illustrate the relation between position of successive items within the series and ST for both nonsense syllables (Le Ny, 1969) and paired associates (Le Ny and DenhiCre, 1970). Zacks ( 1969) showed the existence of a significant positive correlation between ST of pairedassociates and their difficulty, which was defined from the ordination of a control group performance. Le Ny et al. ( 1972), and Martins ( 1972), recently reported that the * We are greatly indebted to Mich&leRobert for her aid in the preparation of this paper.
44
J.-F. le Ny et al.. Study-time of sentences
higher the interstimulus similarity of paired-associates, the longer their ST. In these last two experiments, the same material was used: it consisted of three-digits numbers paired with letters. These numbers were: (a) 446, 466, 644, 664; (b) 336, 774; (c) 011, 899, and they were constructed in order to show respectively: (a) high; (b) medium and (c) low interstimulus similarity. One interpretation of the last result regarding ST may be that the higher the interstimulus similarity, the more information the Ss had to store to achieve the final tasks of recall and recognition: they could indeed analyse the set of stimuli and store one digit at random for the (c) numbers, one digit out of the first two for the (b) numbers, and at least two digits for the (a) numbers. It then appears that ST might depend upon the amount of “mnesic units” which must be stored before complete mastery of the final task. However, another important and consistent result of the abovementioned experiments was that the observed final performance in recall and recognition was also related to the difficulty of the items. In other words, in spite of instructions emphasizing the requirement to attain a perfect retention of the material, regulation of STs as a function of difficulty did allow the occurrence of differences betw,een items on the final retention performance. A tentative interpretation of the mechanisms leading to these results has been proposed (Le Ny et al., 1972), but it may be more generally assumed that the Ss did not store the whole information which was thought to be needed in order to attain a perfect retention of all the items. This line of reasoning may be extended to a semantic material, in which the so-called “mnesic units” are not given by the surface stmcture but theoretically inferred. Two basic ideas then served as a point of departure for the present research: (1) Semantic units. Each morpheme of a sentence may be analysed into semantic units; more precisely one specific word may be considered to provide the same semantic information as another word denoting the superordinate category, (thereafter called “general” morpheme), plus a distinctive information. For instance if we consider respectively the words “laurel” and “lunch” and “meal”, “to hustle” and “to hit”, we may state “bush”, that the former term of each pair carries the same information as the second, plus a complementary specific information. The presence of such a difference of specificity may be submitted to an operational
J.-F. le Ny et al., Study-time of sentences
45
criterion; it may be assumed to exist between the two words whenever a dictionary or a group of judges can give a definition of the first word by using the second plus a semantic addition. How “mnesic units” correspond to these assumed semantic units may be conceived in different ways; for instance this might be done through the representation of a storage of features, or of markers, or of values according to certain dimensions (cf. Bower, 1967; Collins and Quillian, 1969, 1970; Horowitz and Manelis, 1972; Katz and Fodor, 1963; Kintsch, 1970; Norman and Rumelhart, 1970). These conceptions are considered to be equivalent to the present hypothesis in so far as they involve a difference in the information to be stored between a specific and a general word. If we apply at the semantic unit level the above-mentioned hypothesis namely that ST increases with the number of mnesic units to be stored, then we must predict that ST of specific words will be longer than ST of general words. But from the two levels of specificity defined for a set of pairs of words, it is further possible to construct sentences, having a constant syntaxic structure, and constituted either of specific words or of corresponding general words. Two categories of sentences may then be generated, which will also by convention be called “specific” and “general” sentences. Here is an instance of a general and of a specific sentence: Un (A Un (A
arbuste sale bordait la maison. dirty bush was edging the house.) laurier poussi&eux masquait la chaumiere. dusty laurel was screening the thatched cottage.)
As the words of the second sentence are term to term more specific than the words of the former, it may be predicted that ST of the specific sentence will be longer than ST of the general sentence. Learning of whole sentences rather than that of isolated words has been chosen for two main reasons. First the differences between the respective assumed numbers of mnesic units to store ought to be greater - additivity being postulated - with specific and general sentences than with specific and general isolated words. Second, the general words are more often polysemic and their insertion within a sentence appears to be a means of controlling the sense which may be attributed to them by the Ss.
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J.-F. le Ny et al., Study-time of sentences
(2) Semantic exploration. Storage of a more or less important amount of mnesic units - and consequently STs of the sentences may depend not only upon the information carried by the material but also upon the S’s activity of selecting and processing this information; for storage may be related only to part of the material, and in the extreme case S might extract and store from one specific sentence only these semantic units which are contained in the corresponding general sentence. Conversely it might indeed be imagined that one general word could be specified by the activity of an S (for instance through the action of a frequency phenomenon) so that its storage resembles that of a corresponding specific word. This latter eventuality has not been considered here, if not, as it has been said, precisely by using sentences in lieu of single words. We call semantic exploration the activity of selecting and processing the assumed semantic units present in the material and we hypothesize that it may be set to operate through the requirements of the task. A possible way to prevent the occurrence of a limitation to semantic exploration and to storage of the distinctive features of the material is then to compel the S to learn two semantically similar sentences in order to emphasize discriminative learning. For that reason, instead of pairs, triads of sentences were constructed by the above mentioned procedure, with one general and two “parallel” specific sentences. One instance of a second specific sentence (constituting a triad with the two previously cited) follows:
Un fusain crasseux cachait la masure. (A grubby spindle-tree was hiding the hovel.) Each S then had to learn a set of sentences among which some were the only one of their triad (these will be called “isolated” sentences), whereas some others were present in the series either with another sentence of the same triad, but of a different kind (“mixed” sentences) or with another sentence of the same triad and of the same kind (“contrasted” specific sentences). It was predicted that the ST of the contrasted or mixed sentences would be longer than the ST of the isolated sentences.
J.-F. le Ny et al., Study-time of sentences
Experiment
41
1
This experiment aimed to test jointly both predictions presented above, namely that ST would be longer for specific sentences than for general ones, and also for mixed or contrasted sentences than for specific isolated ones.
Method Subjects.
Twenty-four students (both sexes) from the University of Paris-g, volunteered to in this experiment. Material. The whole material was French. It consisted of 19 sentences divided into 6 triads (called a, b, . . . . j) and of another sentence (called k). A uniform structure was adopted to construct the sentences: a subject phrase (article + noun + adjective in a consonant order according to the constraints of the language), a transitive verb, an object phrase (article + noun + adjective in a suitable order). For each triad, first a general sentence (ag bg, . . . . fg) was constructed of which the lexical components might intuitively be considered as general; for each of these general sentences two specific variants (al and a2, bl and b2, . . . . fl and f2) were constructed by substituting each lexical component (articles excluded) with another judged to possess the same principal meaning plus one or several supplementary semantic features; in some cases when it appeared impossible to increase specificity, synonyms or equivalents were used. The substitutions were made so that acceptability of the sentences may be preserved. It was tried not to introduce any difference of specificity between the variants 1 and 2 for a same sentence in such a way that they could be “parallel”. Another example of one triad follows: participate
cg: La jolie femme avait une toilette color&.. cl:
c2:
(The pretty woman had coloured clothes.) La seduisante vendeuse arborait une robe bariolde. (The attractive saleswoman sported a variegated dress.) La ravissante serveuse portait un tailleur chatoyant. (The lovely waitress wore a shimmering suit.)
The specificity of the semantic components was further systematically estimated by a group of judges. AU triads of words, for instance “laurel”, “spindletree”, “bush” or “to have”, “to sport”, “to wear” were mimeographed on sheets, verbs always being foll;wed by a general complement. The order of the words in the triad and of the triads in the list was random; each word was numbered. These sheets were presented to 20 adult Ss. Detailed instructions, with extra-list examples, prescribed them to try to imagine a definition for each word by using another word in the list; Ss had to indicate the number of this defiiing word as a response to the word to be defined, or write a zero if it was impossible. It was found that all the words supposed to be specific received as a response the word supposed to be more general, and all the words supposed to be general received as a response a zero. These results are considered to be a sufficient validation of the rules of construction of the material as far as specificity is concerned. Apparatus. During the learning task, sentences were exposed on a display made up of 30 articulated metallic sheets, which could be turned as book pages. Each sheet showed a typed sentence; three cycles of nine sentences in different order were prepared, each tenth sheet being white and bearing a thumb-index which marked the end of each cycle.
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J.-F. le Ny et al., Study-time of sentences
At the middle of the semi-circle described by the border of the sheet when it was turned, a microswitch had been mounted; whenever one sheet passed in front of it, through an inverter two electronic stopwatches (providing accuracy up to l/100 set) were activated and one stopwatch was started while the other was stopped; E could thus register ST for each sentence. Procedure. Each S was presented with a set of ten sentences, which included the constant sentence k, identical for all Ss, plus nine variable sentences taken among the six triads according to the following rules: (1) Within each of three of the triads was taken one sentence (one g, one 1, and one 2); these were three isoluted sentences; (2) within each of two of the triads were taken together one general sentence and one specific sentence (1 or 2); those were four mixed sentences; (3) within the remaining triads were taken the two specific sentences (1 and 2); those were two contrasted sentences. An instance of such a set follows (in an alphabetical order, different of the presentation order): ag, at, bg bz. cl, ~2, dr, ez.fg k. By permutation were generated six of these sets; 4 Ss were randomly allotted to each one. The order of presentation was random and permuted over the three cycles in order to minimize as much as possible the position effects. S was instructed to learn perfectly the set of sentences to be presented to him, and was told that, at the end of the task, he would be submitted to a test of free recall; during the learning task he could spend as much time he wanted to on each sentence and he himself would have to go on the next sentence by turning the sheets. He could see the sentences as many times he wished, but always in the fixed order of presentation, and he could interrupt this study at the end of any cycle when he thought he knew all the sentences perfectly. It was strongly emphasized that he had to study the items until he knew them perfectly and exactly, and that on the test every modification, eventhough tiny, of meaning, or of content, would be considered asan error. S then proceeded to the learning task; if S went beyond three cycles, E drew back all sheets to their initial position and invited S to continue without interruption. When S judged he knew the sentences perfectly, he interrupted the study at the end of a cycle; after a one minute interval S was given a booklet; during this interval he had been instructed to write on the successive pages of the booklet, in the order he wanted to, all the sentences he remembered. S was allowed 5 min to complete that task. S was then asked whether or not he desired to resume study. If he decided not to resume study, the experiment was ended; if he decided to resume study, he was told that the above mentioned procedure would be repeated and that afterwards he would be given the same test again. After completion of this eventual second phase, no further study was offered thereafter. A post-experimental interview followed the completion of the task.
Results Only 4 out of 24 Ss did resume study after the first testing; due to this small number and also in order to satisfy basic homogeneity requirements, only the results and treatments related to the first period of study for all Ss will be presented here; however, it was verified that the conclusions to be exposed would have been the same had the supplementary period of study of the four Ss been taken into consideration. Within and between subjects comparisons were Study-times of general vs. specific sentences. made on STs of general and specific sentences.
J.-F. le Ny et al., Study-time of sentences
49
(a) When a general and a specific sentence of a given triad were learned by a same S (mixed sentences), it was possible to directly compare the respective STs spent on either a general or a specific sentence. Then for each S we first summed the STs of the two specific sentences, and second the STs of the two general sentences. A sign test was applied to these values; for 19 out of 24 Ss, the difference was in the predicted direction. This proportion is significant at the 0.01 level. (b) When only one sentence of a determined triad was learned by the same S, (isolated sentences), no direct comparison of STs was possible. Then a relative ST was computed for each isolated sentence learned by each S, by dividing its raw ST by the total ST spent on all ten sentences; this value represented the fraction of total ST one S devoted to a given sentence, and was called a study ratio (SR). All the between subjects comparisons were performed upon these SRs and, as their distributions were questionable, the sign test was used. In the present case, the SRs of four Ss were available for each general or specific sentence; a mean was computed upon them. Then a sign test was applied to the comparisons of the mean SR of the 12 specific sentences with the corresponding general sentence’s mean SR. For 10 out of 12 of these comparisons, SR of specific sentences was larger than SR of corresponding general sentences; this result is significant at the 0.05 level. Study-time of isolated vs. mixed or contrasted sentences. Only between Ss comparisons of SR were possible with regard to isolated and mixed or contrasted sentences. Three kinds of these comparisons were performed: (a) SR of specific isolated vs specific mixed sentences; 7 out of 12 comparisons were in the predicted direction; this result is non-significant. (b) SR of specific isolated vs. contrasted sentences; 8 out of 12 comparisons were in the predicted direction; this result is non-significant. (c) SR of general isolated vs general mixed sentences; 6 out of 12 comparisons were in the predicted direction; this result in non-significant. Recall. The average number of perfectly recalled sentences was 4.3. Comparisons of the numbers of general vs. specific, or of isolated vs. mixed recalled sentences for each S, and application of the sign test, showed no significant difference. Since no modification of the syntactic structure was observed in the incorrectly recalled sentences, a more detailed analysis, taking into consideration the numbers of words correctly recalled in their correct position was also performed. Once more no significant difference was found between recall of the different kinds of sentences.
Experiment
2
In exp. 1, SRs of specific isolated and contrasted sentences differed in the predicted direction, but this difference did not reach significance. Exp. 2 tried to test the same hypothesis following the same procedure, but excluding general sentences. Since it appeared from exp. 1 that having ten sentences to store was long and difficult, and that through this factor the Ss might have been inclined to stop their study before adequate mastery was attained, consequently only eight sentences were used. Moreover the following possibility arose: it is conceivable that, during the learning of contrasted sentences, mental comparison of these sentences took a proeminent part. It may be supposed that it occurred in presence of a given contrasted sentence through a memory search of the corresponding parallel sentence. One way to modify this activity was to vary the temporal proximity of the two contrasted sentences in the series: if the second was distant from the first in the series, and separated from it by several interpolated sentences, search and
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J.-F. le Ny et al., Study-time of sentences
comparison then ought to be disturbed. It was thus hypothesized that ST or SR of distant contrasted sentences would be greater than ST or SR of adjacent contrasted sentences.
Method Subjects. Eighteen students from the University of Paris-8 served as Ss. Mote&L The six pairs of specific sentences and the apparatus were those used in exp. 1. Procedure. The general procedure was the same as in exp. 1. Each S was presented with eight sentences, namely: (1) two pairs of parallel sentences (i.e. four contrasted sentences); (2) one sentence of each of the four remaining pairs (i.e. four isolated sentences). Three sets of sentences were so established. In each set or series the contrasted sentences of one pair were always presented adjacently, whereas the sentences of the other pair were separated by three interpolated sentences; these three were variable and could include or not the adjacent contrasted pair. Adjacent or distant contrasted sentences were presented in a variable order. According to this rule 6 serial orders were constructed which generated 18 series; Ss were allotted to these series as they came to participate in the experiment.
Results Fifteen Ss out of 18 resumed study after the first recall. Total ST for each of the Ss before they interrupted study (i.e. for two phases of study for 15 Ss and for one phase for 3 Ss) was taken into consideration. It was verified that the general conclusions would have been the same if only the first phase had been taken into consideration. Study-times of isoloted vs. contrasted sentences. (a) Within subjects comparisons: for each of the 18 Ss was computed the total ST spent on the 4 isolated and contrasted sentences. A sign test was applied to these values. For 17 out of 18 Ss, total ST of the contrasted sentences was longer than total ST of the isolated sentences. This proportion was significant beyond the 0.01 level. (b) Between subjects comparisons: the average ST of each sentence was computed separately in view of the fact that it had been presented isolated (to 9 Ss) or contrasted (to 9 other Ss), and a sign test was applied. For the 12 sentences, STs of contrasted sentences were longer than STs of isolated sentences (proportion significant beyond the 0.01 level). Study-times of adjacent vs. distant contrasted sentences. Comparison of the average STs of these two categories of sentences showed no significant difference. However if the successive cycles of study were distinguished, it appeared that, during the first cycle, ST of the adjacent contrasted sentences was, contrary to the hypothesis, longer than STs of the distant contrasted sentences for 14 Ss out of 18 (proportion significant at the 0.05 level). This difference did not persist during the subsequent cycles. R ecoll. In the first test, the average number of perfectly recalled sentences was 4.48 for the isolated sentences and 5.68 for the contrasted sentences (5.76 for the adjacent and 5.60 for the distant sentences). By comparing the numbers of perfectly recalled sentences for each S in each category, no significant difference was found (Student’s t). However, since no modification of the syntactic structures was observed, as in exp. 1, the numbers of words correctly recalled in the correct position by each S were calculated and compared for contrasted and isolated sentences; the value of the Student’s t was 2.33, slgnfi
J.-F. le Ny et al., Study-time of sentences
51
cant at the 0.05 level. It may then be concluded that recall of the content of contrasted sentences was higher than that of isolated sentences. In the second test, the average number of perfectly recalled sentences for the 15 Ss who resumed study, was 6.04 for the isolated sentences and 5.61 for the contrasted sentences. No significant difference was found between these numbers nor between the corresponding numbers of correctly recalled words.
Discussion The results of exp. 1 substantiate the conclusion that, in self-paced learning, ST depends upon the nature of the material. After item position, stimulus similarity and raw difficulty, one further characteristic of the material, namely the one defined here as specificity, was found to have an effect upon ST. Indeed specificity of a word is commonly known to be correlated with other variables such as length, frequency, familiarity, extension of the denoted class, associative value, polysemy, imagery value, etc. Still, much remains to be done in order to separate the relations between ST and these different characteristics from the one studied here, and to ascertain this latter. The present data point to the fact that some of the relations between ST and the mentioned variables also ought to be significant. However that may be, the results provided a new confirmation of the existence of the regulation of ST as a function of the nature of the material. A second conclusion to be drawn from exp. 1 and 2 is that, for a given part of the material, ST depends upon the learning activity. These results are in agreement with the presented hypothesis, namely that a difference between STs of isolated sentences and contrasted sentences ought to occur as a result of an assumed particular mental activity called semantic exploration. It might be argued that discriminative learning, which obviously took place when contrasted sentences were presented, might have not been necessarily of a semantic nature, but might have been performed at a lower level as in rote learning. However one result points against this argument: in exp. 1, no difference at all was found between STs of isolated and mixed genera2 sentences whereas such a difference, though non significant, existed between STs of isolated and mixed or contrasted specific sentences; this latter result was confirmed by exp. 2. Such a fact may be explained if we assume that the same information
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J.-F. le Ny et al., Study-time of sentences
was explored and processed in general sentences, whether they were isolated or mixed, whereas a different information was explored and processed in specific sentences according to the fact that they were isolated or contrasted; if so, this calls for a semantic interpretation. Another result is consistent with this role of exploration: the higher rate of recall of the contrasted sentences in comparison with the isolated ones on the first test of exp. 2. It had been observed repeatedly in previous experiments (Le Ny, 1969; Le Ny and DenhiG!re, 1970; Le Ny et al., 1972) that the characteristics of the material - position within the series, or interstimulus similarity - had a similar effect upon ST and performance of the Ss; in other words, recall of the parts of the material upon which the Ss spent a longer ST was lower than that of the parts with shorter ST. Now in exp. 2 we have found an opposite relation between ST recorded during the first period of study and performance on the first test: recall of the sentences upon which the Ss spent a longer ST was higher than that of sentences with shorter ST. Although this relation did not hold for the second period of study and the second test, such a discrepancy must be explained. This may be done if we consider that the relation between ST and subsequent recall performance is two-faced: (a) as to intrinsic difficulty of the material, both are dependant variables, but ought to vary in opposite directions: the more difficult the material, the longer the ST and the poorer the performance: (b) as to S’s activity, performance is a variable dependant upon ST, and varying in the same direction: for a determined material and a given S, the longer the ST, the better the performance. From these considerations, we deduce that variations of ST and performance occurring in the same direction are a sign of unequal processing of a same material. However, it is clear that this orientation of activity may change in the course of learning, as it is indicated by the fact that the differences in test performance were not maintained on the second test. The results pertaining to the effect of temporal distance of the contrasted sentences show another example of such an evolution: a difference contrary to the one expected occurred in the first cycle, but none in the subsequent ones. In fact, after the experiment several Ss reported that for the first cycle, they compared only the present sentence to the previous adjacent one, and not to the distant one, which was not well remembered; for the later cycles all contrasted sentences, adjacent or distant, were compared similarly. Thus comparison was used, but differently according to the cycles.
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References Bower, G.H., 1967. A multicomponent theory of the memory trace. In: K.W. Spence and J.T. Spence (eds.), The psychology of learning and motivation, vol. 1, New York: Academic Press. Collins, A.M. and M.R. Quillian, 1969. Retrieval time from semantic memory, Journal of Verbal Learning and Verbal Behavior 8240-247. Collins, A.M. and M.R. Quillian, 1970. Facilitating retrieval from semantic memory: the effect of repeating part of an inference. In: A.F. Sanders (ed.), Attention and performance III, Acta Psychologica 33, 304-3 14. Horowitz, L.M. and L. Manelis, 1972. Towards a theory of redintegrative memory. In: G.H. Bower and J.T. Spence (eds.), The psychology of learning and motivation, vol. 5, New York: Academic Press. Katz, J.J. and J.A. Fodor, 1963. The structure of a semantic theory, Language 39, 170-210. Kintsch, W., 1970. Models for free recall and recognition. In: D.A. Norman (ed.), Models of human memory, New York: Academic Press. Le Ny, J.F., 1969. L’effet de position dam un apprentissage intentionnel de drie, Annde Psychologique 69, 81-92. Le Ny, J.F. and G. Denhiere, 1970. L’apprentissage a allure lrbre de couples associ&, Psychologie Frangaise 15, 18-29. Le Ny, J.F., G. Denhiere and D. Le Taillanter, 1972. Regulation of study-time and interstimulus similarity in self-paced learning conditions, Acta Psychologica 36,280-289. Martins, D., 1972. L’influence de rappels rep&& sur la performance finale dam une t&he d’apprentissage a allure libre, Amr6e Psychologique, in press. Norman, D.A. and D.E. Rumelhart, 1970. A system for perception and memory. In: D.A. Norman (ed.), Models of human memory, New York: Academic Press. Zacks, R.T., 1969. Invariance of total learning time under different conditions of practice, Journal of Experimental Psychology 82,441-447.
STUDY-TIME
OF SENTENCES AS A FUNCTION OF THEIR
SPECIFICITY AND OF SEMANTIC EXPLORATION Jean-Fraqois
LE NY, Guy DENHIkRE
and Danielle LE TAILLANTER*
University of Paris 8, France Accepted October 20, 1972
In self-paced learning conditions the study-time of sentences is supposed to depend jointly upon the informative content of the material and upon its exploration by the subject in the course of learning. In exp. 1 informative content was varied by using sentences constituted either of general or of specific words; study-time was found to be significantly longer for the latter sentences than for the former and the recall performance to be equal. Differential semantic exploration and storage were instigated by presenting in the series either pairs of similar, and thereby contrasted sentences, or isolated sentences. In exp. 2, study-time of the former sentences was longer than that of the latter; but the first recall performance recorded with the contrasted sentences was also higher. The divergent effects of the nature of the material and of the activity of the subject upon study-time and recall performance were emphasized.
It has been previously shown in several experiments that Ss placed in a self-paced learning situation regulate their study-time (ST) according to the difficulty of the different parts of the material. Factors exerting an influence upon the number of repetitions necessary to learn an item in conventional situations, or upon the number of errors after a fixed amount of time devoted to learning, also have an effect upon self-paced ST. For instance, in self-paced serial learning, an inverted-U curve was found to illustrate the relation between position of successive items within the series and ST for both nonsense syllables (Le Ny, 1969) and paired associates (Le Ny and DenhiCre, 1970). Zacks ( 1969) showed the existence of a significant positive correlation between ST of pairedassociates and their difficulty, which was defined from the ordination of a control group performance. Le Ny et al. ( 1972), and Martins ( 1972), recently reported that the * We are greatly indebted to Mich&leRobert for her aid in the preparation of this paper.
44
J.-F. le Ny et al.. Study-time of sentences
higher the interstimulus similarity of paired-associates, the longer their ST. In these last two experiments, the same material was used: it consisted of three-digits numbers paired with letters. These numbers were: (a) 446, 466, 644, 664; (b) 336, 774; (c) 011, 899, and they were constructed in order to show respectively: (a) high; (b) medium and (c) low interstimulus similarity. One interpretation of the last result regarding ST may be that the higher the interstimulus similarity, the more information the Ss had to store to achieve the final tasks of recall and recognition: they could indeed analyse the set of stimuli and store one digit at random for the (c) numbers, one digit out of the first two for the (b) numbers, and at least two digits for the (a) numbers. It then appears that ST might depend upon the amount of “mnesic units” which must be stored before complete mastery of the final task. However, another important and consistent result of the abovementioned experiments was that the observed final performance in recall and recognition was also related to the difficulty of the items. In other words, in spite of instructions emphasizing the requirement to attain a perfect retention of the material, regulation of STs as a function of difficulty did allow the occurrence of differences betw,een items on the final retention performance. A tentative interpretation of the mechanisms leading to these results has been proposed (Le Ny et al., 1972), but it may be more generally assumed that the Ss did not store the whole information which was thought to be needed in order to attain a perfect retention of all the items. This line of reasoning may be extended to a semantic material, in which the so-called “mnesic units” are not given by the surface stmcture but theoretically inferred. Two basic ideas then served as a point of departure for the present research: (1) Semantic units. Each morpheme of a sentence may be analysed into semantic units; more precisely one specific word may be considered to provide the same semantic information as another word denoting the superordinate category, (thereafter called “general” morpheme), plus a distinctive information. For instance if we consider respectively the words “laurel” and “lunch” and “meal”, “to hustle” and “to hit”, we may state “bush”, that the former term of each pair carries the same information as the second, plus a complementary specific information. The presence of such a difference of specificity may be submitted to an operational
J.-F. le Ny et al., Study-time of sentences
45
criterion; it may be assumed to exist between the two words whenever a dictionary or a group of judges can give a definition of the first word by using the second plus a semantic addition. How “mnesic units” correspond to these assumed semantic units may be conceived in different ways; for instance this might be done through the representation of a storage of features, or of markers, or of values according to certain dimensions (cf. Bower, 1967; Collins and Quillian, 1969, 1970; Horowitz and Manelis, 1972; Katz and Fodor, 1963; Kintsch, 1970; Norman and Rumelhart, 1970). These conceptions are considered to be equivalent to the present hypothesis in so far as they involve a difference in the information to be stored between a specific and a general word. If we apply at the semantic unit level the above-mentioned hypothesis namely that ST increases with the number of mnesic units to be stored, then we must predict that ST of specific words will be longer than ST of general words. But from the two levels of specificity defined for a set of pairs of words, it is further possible to construct sentences, having a constant syntaxic structure, and constituted either of specific words or of corresponding general words. Two categories of sentences may then be generated, which will also by convention be called “specific” and “general” sentences. Here is an instance of a general and of a specific sentence: Un (A Un (A
arbuste sale bordait la maison. dirty bush was edging the house.) laurier poussi&eux masquait la chaumiere. dusty laurel was screening the thatched cottage.)
As the words of the second sentence are term to term more specific than the words of the former, it may be predicted that ST of the specific sentence will be longer than ST of the general sentence. Learning of whole sentences rather than that of isolated words has been chosen for two main reasons. First the differences between the respective assumed numbers of mnesic units to store ought to be greater - additivity being postulated - with specific and general sentences than with specific and general isolated words. Second, the general words are more often polysemic and their insertion within a sentence appears to be a means of controlling the sense which may be attributed to them by the Ss.
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(2) Semantic exploration. Storage of a more or less important amount of mnesic units - and consequently STs of the sentences may depend not only upon the information carried by the material but also upon the S’s activity of selecting and processing this information; for storage may be related only to part of the material, and in the extreme case S might extract and store from one specific sentence only these semantic units which are contained in the corresponding general sentence. Conversely it might indeed be imagined that one general word could be specified by the activity of an S (for instance through the action of a frequency phenomenon) so that its storage resembles that of a corresponding specific word. This latter eventuality has not been considered here, if not, as it has been said, precisely by using sentences in lieu of single words. We call semantic exploration the activity of selecting and processing the assumed semantic units present in the material and we hypothesize that it may be set to operate through the requirements of the task. A possible way to prevent the occurrence of a limitation to semantic exploration and to storage of the distinctive features of the material is then to compel the S to learn two semantically similar sentences in order to emphasize discriminative learning. For that reason, instead of pairs, triads of sentences were constructed by the above mentioned procedure, with one general and two “parallel” specific sentences. One instance of a second specific sentence (constituting a triad with the two previously cited) follows:
Un fusain crasseux cachait la masure. (A grubby spindle-tree was hiding the hovel.) Each S then had to learn a set of sentences among which some were the only one of their triad (these will be called “isolated” sentences), whereas some others were present in the series either with another sentence of the same triad, but of a different kind (“mixed” sentences) or with another sentence of the same triad and of the same kind (“contrasted” specific sentences). It was predicted that the ST of the contrasted or mixed sentences would be longer than the ST of the isolated sentences.
J.-F. le Ny et al., Study-time of sentences
Experiment
41
1
This experiment aimed to test jointly both predictions presented above, namely that ST would be longer for specific sentences than for general ones, and also for mixed or contrasted sentences than for specific isolated ones.
Method Subjects.
Twenty-four students (both sexes) from the University of Paris-g, volunteered to in this experiment. Material. The whole material was French. It consisted of 19 sentences divided into 6 triads (called a, b, . . . . j) and of another sentence (called k). A uniform structure was adopted to construct the sentences: a subject phrase (article + noun + adjective in a consonant order according to the constraints of the language), a transitive verb, an object phrase (article + noun + adjective in a suitable order). For each triad, first a general sentence (ag bg, . . . . fg) was constructed of which the lexical components might intuitively be considered as general; for each of these general sentences two specific variants (al and a2, bl and b2, . . . . fl and f2) were constructed by substituting each lexical component (articles excluded) with another judged to possess the same principal meaning plus one or several supplementary semantic features; in some cases when it appeared impossible to increase specificity, synonyms or equivalents were used. The substitutions were made so that acceptability of the sentences may be preserved. It was tried not to introduce any difference of specificity between the variants 1 and 2 for a same sentence in such a way that they could be “parallel”. Another example of one triad follows: participate
cg: La jolie femme avait une toilette color&.. cl:
c2:
(The pretty woman had coloured clothes.) La seduisante vendeuse arborait une robe bariolde. (The attractive saleswoman sported a variegated dress.) La ravissante serveuse portait un tailleur chatoyant. (The lovely waitress wore a shimmering suit.)
The specificity of the semantic components was further systematically estimated by a group of judges. AU triads of words, for instance “laurel”, “spindletree”, “bush” or “to have”, “to sport”, “to wear” were mimeographed on sheets, verbs always being foll;wed by a general complement. The order of the words in the triad and of the triads in the list was random; each word was numbered. These sheets were presented to 20 adult Ss. Detailed instructions, with extra-list examples, prescribed them to try to imagine a definition for each word by using another word in the list; Ss had to indicate the number of this defiiing word as a response to the word to be defined, or write a zero if it was impossible. It was found that all the words supposed to be specific received as a response the word supposed to be more general, and all the words supposed to be general received as a response a zero. These results are considered to be a sufficient validation of the rules of construction of the material as far as specificity is concerned. Apparatus. During the learning task, sentences were exposed on a display made up of 30 articulated metallic sheets, which could be turned as book pages. Each sheet showed a typed sentence; three cycles of nine sentences in different order were prepared, each tenth sheet being white and bearing a thumb-index which marked the end of each cycle.
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At the middle of the semi-circle described by the border of the sheet when it was turned, a microswitch had been mounted; whenever one sheet passed in front of it, through an inverter two electronic stopwatches (providing accuracy up to l/100 set) were activated and one stopwatch was started while the other was stopped; E could thus register ST for each sentence. Procedure. Each S was presented with a set of ten sentences, which included the constant sentence k, identical for all Ss, plus nine variable sentences taken among the six triads according to the following rules: (1) Within each of three of the triads was taken one sentence (one g, one 1, and one 2); these were three isoluted sentences; (2) within each of two of the triads were taken together one general sentence and one specific sentence (1 or 2); those were four mixed sentences; (3) within the remaining triads were taken the two specific sentences (1 and 2); those were two contrasted sentences. An instance of such a set follows (in an alphabetical order, different of the presentation order): ag, at, bg bz. cl, ~2, dr, ez.fg k. By permutation were generated six of these sets; 4 Ss were randomly allotted to each one. The order of presentation was random and permuted over the three cycles in order to minimize as much as possible the position effects. S was instructed to learn perfectly the set of sentences to be presented to him, and was told that, at the end of the task, he would be submitted to a test of free recall; during the learning task he could spend as much time he wanted to on each sentence and he himself would have to go on the next sentence by turning the sheets. He could see the sentences as many times he wished, but always in the fixed order of presentation, and he could interrupt this study at the end of any cycle when he thought he knew all the sentences perfectly. It was strongly emphasized that he had to study the items until he knew them perfectly and exactly, and that on the test every modification, eventhough tiny, of meaning, or of content, would be considered asan error. S then proceeded to the learning task; if S went beyond three cycles, E drew back all sheets to their initial position and invited S to continue without interruption. When S judged he knew the sentences perfectly, he interrupted the study at the end of a cycle; after a one minute interval S was given a booklet; during this interval he had been instructed to write on the successive pages of the booklet, in the order he wanted to, all the sentences he remembered. S was allowed 5 min to complete that task. S was then asked whether or not he desired to resume study. If he decided not to resume study, the experiment was ended; if he decided to resume study, he was told that the above mentioned procedure would be repeated and that afterwards he would be given the same test again. After completion of this eventual second phase, no further study was offered thereafter. A post-experimental interview followed the completion of the task.
Results Only 4 out of 24 Ss did resume study after the first testing; due to this small number and also in order to satisfy basic homogeneity requirements, only the results and treatments related to the first period of study for all Ss will be presented here; however, it was verified that the conclusions to be exposed would have been the same had the supplementary period of study of the four Ss been taken into consideration. Within and between subjects comparisons were Study-times of general vs. specific sentences. made on STs of general and specific sentences.
J.-F. le Ny et al., Study-time of sentences
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(a) When a general and a specific sentence of a given triad were learned by a same S (mixed sentences), it was possible to directly compare the respective STs spent on either a general or a specific sentence. Then for each S we first summed the STs of the two specific sentences, and second the STs of the two general sentences. A sign test was applied to these values; for 19 out of 24 Ss, the difference was in the predicted direction. This proportion is significant at the 0.01 level. (b) When only one sentence of a determined triad was learned by the same S, (isolated sentences), no direct comparison of STs was possible. Then a relative ST was computed for each isolated sentence learned by each S, by dividing its raw ST by the total ST spent on all ten sentences; this value represented the fraction of total ST one S devoted to a given sentence, and was called a study ratio (SR). All the between subjects comparisons were performed upon these SRs and, as their distributions were questionable, the sign test was used. In the present case, the SRs of four Ss were available for each general or specific sentence; a mean was computed upon them. Then a sign test was applied to the comparisons of the mean SR of the 12 specific sentences with the corresponding general sentence’s mean SR. For 10 out of 12 of these comparisons, SR of specific sentences was larger than SR of corresponding general sentences; this result is significant at the 0.05 level. Study-time of isolated vs. mixed or contrasted sentences. Only between Ss comparisons of SR were possible with regard to isolated and mixed or contrasted sentences. Three kinds of these comparisons were performed: (a) SR of specific isolated vs specific mixed sentences; 7 out of 12 comparisons were in the predicted direction; this result is non-significant. (b) SR of specific isolated vs. contrasted sentences; 8 out of 12 comparisons were in the predicted direction; this result is non-significant. (c) SR of general isolated vs general mixed sentences; 6 out of 12 comparisons were in the predicted direction; this result in non-significant. Recall. The average number of perfectly recalled sentences was 4.3. Comparisons of the numbers of general vs. specific, or of isolated vs. mixed recalled sentences for each S, and application of the sign test, showed no significant difference. Since no modification of the syntactic structure was observed in the incorrectly recalled sentences, a more detailed analysis, taking into consideration the numbers of words correctly recalled in their correct position was also performed. Once more no significant difference was found between recall of the different kinds of sentences.
Experiment
2
In exp. 1, SRs of specific isolated and contrasted sentences differed in the predicted direction, but this difference did not reach significance. Exp. 2 tried to test the same hypothesis following the same procedure, but excluding general sentences. Since it appeared from exp. 1 that having ten sentences to store was long and difficult, and that through this factor the Ss might have been inclined to stop their study before adequate mastery was attained, consequently only eight sentences were used. Moreover the following possibility arose: it is conceivable that, during the learning of contrasted sentences, mental comparison of these sentences took a proeminent part. It may be supposed that it occurred in presence of a given contrasted sentence through a memory search of the corresponding parallel sentence. One way to modify this activity was to vary the temporal proximity of the two contrasted sentences in the series: if the second was distant from the first in the series, and separated from it by several interpolated sentences, search and
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comparison then ought to be disturbed. It was thus hypothesized that ST or SR of distant contrasted sentences would be greater than ST or SR of adjacent contrasted sentences.
Method Subjects. Eighteen students from the University of Paris-8 served as Ss. Mote&L The six pairs of specific sentences and the apparatus were those used in exp. 1. Procedure. The general procedure was the same as in exp. 1. Each S was presented with eight sentences, namely: (1) two pairs of parallel sentences (i.e. four contrasted sentences); (2) one sentence of each of the four remaining pairs (i.e. four isolated sentences). Three sets of sentences were so established. In each set or series the contrasted sentences of one pair were always presented adjacently, whereas the sentences of the other pair were separated by three interpolated sentences; these three were variable and could include or not the adjacent contrasted pair. Adjacent or distant contrasted sentences were presented in a variable order. According to this rule 6 serial orders were constructed which generated 18 series; Ss were allotted to these series as they came to participate in the experiment.
Results Fifteen Ss out of 18 resumed study after the first recall. Total ST for each of the Ss before they interrupted study (i.e. for two phases of study for 15 Ss and for one phase for 3 Ss) was taken into consideration. It was verified that the general conclusions would have been the same if only the first phase had been taken into consideration. Study-times of isoloted vs. contrasted sentences. (a) Within subjects comparisons: for each of the 18 Ss was computed the total ST spent on the 4 isolated and contrasted sentences. A sign test was applied to these values. For 17 out of 18 Ss, total ST of the contrasted sentences was longer than total ST of the isolated sentences. This proportion was significant beyond the 0.01 level. (b) Between subjects comparisons: the average ST of each sentence was computed separately in view of the fact that it had been presented isolated (to 9 Ss) or contrasted (to 9 other Ss), and a sign test was applied. For the 12 sentences, STs of contrasted sentences were longer than STs of isolated sentences (proportion significant beyond the 0.01 level). Study-times of adjacent vs. distant contrasted sentences. Comparison of the average STs of these two categories of sentences showed no significant difference. However if the successive cycles of study were distinguished, it appeared that, during the first cycle, ST of the adjacent contrasted sentences was, contrary to the hypothesis, longer than STs of the distant contrasted sentences for 14 Ss out of 18 (proportion significant at the 0.05 level). This difference did not persist during the subsequent cycles. R ecoll. In the first test, the average number of perfectly recalled sentences was 4.48 for the isolated sentences and 5.68 for the contrasted sentences (5.76 for the adjacent and 5.60 for the distant sentences). By comparing the numbers of perfectly recalled sentences for each S in each category, no significant difference was found (Student’s t). However, since no modification of the syntactic structures was observed, as in exp. 1, the numbers of words correctly recalled in the correct position by each S were calculated and compared for contrasted and isolated sentences; the value of the Student’s t was 2.33, slgnfi
J.-F. le Ny et al., Study-time of sentences
51
cant at the 0.05 level. It may then be concluded that recall of the content of contrasted sentences was higher than that of isolated sentences. In the second test, the average number of perfectly recalled sentences for the 15 Ss who resumed study, was 6.04 for the isolated sentences and 5.61 for the contrasted sentences. No significant difference was found between these numbers nor between the corresponding numbers of correctly recalled words.
Discussion The results of exp. 1 substantiate the conclusion that, in self-paced learning, ST depends upon the nature of the material. After item position, stimulus similarity and raw difficulty, one further characteristic of the material, namely the one defined here as specificity, was found to have an effect upon ST. Indeed specificity of a word is commonly known to be correlated with other variables such as length, frequency, familiarity, extension of the denoted class, associative value, polysemy, imagery value, etc. Still, much remains to be done in order to separate the relations between ST and these different characteristics from the one studied here, and to ascertain this latter. The present data point to the fact that some of the relations between ST and the mentioned variables also ought to be significant. However that may be, the results provided a new confirmation of the existence of the regulation of ST as a function of the nature of the material. A second conclusion to be drawn from exp. 1 and 2 is that, for a given part of the material, ST depends upon the learning activity. These results are in agreement with the presented hypothesis, namely that a difference between STs of isolated sentences and contrasted sentences ought to occur as a result of an assumed particular mental activity called semantic exploration. It might be argued that discriminative learning, which obviously took place when contrasted sentences were presented, might have not been necessarily of a semantic nature, but might have been performed at a lower level as in rote learning. However one result points against this argument: in exp. 1, no difference at all was found between STs of isolated and mixed genera2 sentences whereas such a difference, though non significant, existed between STs of isolated and mixed or contrasted specific sentences; this latter result was confirmed by exp. 2. Such a fact may be explained if we assume that the same information
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was explored and processed in general sentences, whether they were isolated or mixed, whereas a different information was explored and processed in specific sentences according to the fact that they were isolated or contrasted; if so, this calls for a semantic interpretation. Another result is consistent with this role of exploration: the higher rate of recall of the contrasted sentences in comparison with the isolated ones on the first test of exp. 2. It had been observed repeatedly in previous experiments (Le Ny, 1969; Le Ny and DenhiG!re, 1970; Le Ny et al., 1972) that the characteristics of the material - position within the series, or interstimulus similarity - had a similar effect upon ST and performance of the Ss; in other words, recall of the parts of the material upon which the Ss spent a longer ST was lower than that of the parts with shorter ST. Now in exp. 2 we have found an opposite relation between ST recorded during the first period of study and performance on the first test: recall of the sentences upon which the Ss spent a longer ST was higher than that of sentences with shorter ST. Although this relation did not hold for the second period of study and the second test, such a discrepancy must be explained. This may be done if we consider that the relation between ST and subsequent recall performance is two-faced: (a) as to intrinsic difficulty of the material, both are dependant variables, but ought to vary in opposite directions: the more difficult the material, the longer the ST and the poorer the performance: (b) as to S’s activity, performance is a variable dependant upon ST, and varying in the same direction: for a determined material and a given S, the longer the ST, the better the performance. From these considerations, we deduce that variations of ST and performance occurring in the same direction are a sign of unequal processing of a same material. However, it is clear that this orientation of activity may change in the course of learning, as it is indicated by the fact that the differences in test performance were not maintained on the second test. The results pertaining to the effect of temporal distance of the contrasted sentences show another example of such an evolution: a difference contrary to the one expected occurred in the first cycle, but none in the subsequent ones. In fact, after the experiment several Ss reported that for the first cycle, they compared only the present sentence to the previous adjacent one, and not to the distant one, which was not well remembered; for the later cycles all contrasted sentences, adjacent or distant, were compared similarly. Thus comparison was used, but differently according to the cycles.
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References Bower, G.H., 1967. A multicomponent theory of the memory trace. In: K.W. Spence and J.T. Spence (eds.), The psychology of learning and motivation, vol. 1, New York: Academic Press. Collins, A.M. and M.R. Quillian, 1969. Retrieval time from semantic memory, Journal of Verbal Learning and Verbal Behavior 8240-247. Collins, A.M. and M.R. Quillian, 1970. Facilitating retrieval from semantic memory: the effect of repeating part of an inference. In: A.F. Sanders (ed.), Attention and performance III, Acta Psychologica 33, 304-3 14. Horowitz, L.M. and L. Manelis, 1972. Towards a theory of redintegrative memory. In: G.H. Bower and J.T. Spence (eds.), The psychology of learning and motivation, vol. 5, New York: Academic Press. Katz, J.J. and J.A. Fodor, 1963. The structure of a semantic theory, Language 39, 170-210. Kintsch, W., 1970. Models for free recall and recognition. In: D.A. Norman (ed.), Models of human memory, New York: Academic Press. Le Ny, J.F., 1969. L’effet de position dam un apprentissage intentionnel de drie, Annde Psychologique 69, 81-92. Le Ny, J.F. and G. Denhiere, 1970. L’apprentissage a allure lrbre de couples associ&, Psychologie Frangaise 15, 18-29. Le Ny, J.F., G. Denhiere and D. Le Taillanter, 1972. Regulation of study-time and interstimulus similarity in self-paced learning conditions, Acta Psychologica 36,280-289. Martins, D., 1972. L’influence de rappels rep&& sur la performance finale dam une t&he d’apprentissage a allure libre, Amr6e Psychologique, in press. Norman, D.A. and D.E. Rumelhart, 1970. A system for perception and memory. In: D.A. Norman (ed.), Models of human memory, New York: Academic Press. Zacks, R.T., 1969. Invariance of total learning time under different conditions of practice, Journal of Experimental Psychology 82,441-447.