Joel Zimmerman

Further evidence on the MP-DP effect in free-recall learning

In Experiment 1, rate and frequency of presentation, concrete and abstract words, and imagery instructions were manipulated along with MP and DP schedules in a long free-recall list, presented for one trial. Large differences between MP and DP were found, but none of the other variables except frequency interacted with MP-DP. In Experiment 2, various forms of MP and DP patternings were used with all words presented four times. Recall was predictable by the number of distributed points within the patterns. In Experiment 3, S paced himself through a long list of words presented on slides. The usual MP-DP differences in recall were present, and parallel differences were observed in exposure times. The difference in MP and DP recall was greater than could be accounted for by differences in exposure time. All experiments showed recall to be related to the input position of the words.

The Syllable as a Source of Error in Multisyllable Word Recognition.

Two-syllable words were presented singly for followed by a two-alternative, forced-choice recognition test. Half of the new words on the test (I words) were constructed by combining two syllables taken from two different study words, and half were neutral words (C words). If, as a consequence of study, the memory for a word carries frequency information about each syllable of multisyllable words, the number of errors produced by choosing I words should be greater than the number produced by choosing C words. The results supported this expectation. Furthermore, differences which occurred during the test suggested that syllabic frequency was further increased during testing. Frequency induction to elements of larger units was proposed as the mechanism by which formal similarity influences recognition.

On the independence of judged frequencies for items presented in successive lists

In an experiment examining retroactive interference effects in a frequency-judging task, all Ss were presented with a list of words occurring varying numbers of times according to either a massed- or distributed-practive (MP or DP) schedule. They were then asked to judge how often each word had occurred. Following this, Ss were given one of four types of second tasks a second list with different items followed by a frequency-judging task for that list (Condition New): a second list with items repeated from the first list but with different frequencies for each item, while either maintaining items as either MP or DP items (Condition Same) or switching MP items to DP, and vice versa (Condition Reverse): followed by a frequency-judging task for the second-list frequencies only: or a puzzle task for the amount of time required for second-list presentation and judgment in the other conditions (Condition None). Finally, all Ss were asked to recall List 1 frequencies, List 2 frequencies were less discriminable in Conditions Same and Reverse than in Condition New. Recall of List 1 frequencies, however, was not different for these three groups, but was poorer than in List 2 frequency judgments were not independent of List 1 frequencies.

The spacing effect in the learning of word pairs

Following the presentation of a single list of word pairs consisting of a three-letter word on the left and a five-letter word on the right, groups of 64 Ss each were asked to recall the (a) three-letter words, (b) five-letter words, (c) intact pairs, or (d) five-letter words with the three-letter words provided. Two types of repeated pairs were presented, one in which the same three- and five-letter words were repeated together (same pairs) and one in which the same five-letter word was repeated with different three-letter words (different pairs). For half of the Ss in each recall group, the repetitions of a pair containing a given five-letter word were massed (MP); for the other half, the repetitions were distributed (DP). Recall of MP same pairs and the eomponents of these pairs was consistently poorer than that of DP same pairs. Recall of the repeated component of the different pairs was also poorer under MP than under DP. The results were interpreted as supportive of an attenuation-of-attention explanation of the spacing effect.

Learning-to-learn verbal-discrimination lists

Subjects learned 7 successive 24-pair verbal-discrimination (VD) lists over 3 days. Group 1 had typical VD lists (Type 1). Group 2 had lists in which each wrong word was used twice in the list (Type 2). Group 1-2 learned 4 Type-1 lists followed by 3 Type-2 lists, and Group 2-1 had the reverse schedule. Learning-to-learn was greater for Type-2 than for Type-1 lists. A decrement in performance on the first list of Days 2 and 3 was tentatively identified as being due to lack of warmup which influenced rehearsal efforts. The ability to discriminate frequency differences correlated substantially with the ability to learn VD lists.

A Comparison of the Effects of Formal Similarity among Trigrams and among Word Triads.

The central question of this report concerned the role of formal similarity in free recall of lists of trigrams and lists of three-letter word triads. Similarity was manipulated among trigrams by duplicating letters and among triads by duplicating words. An initial study showed that lists of 16 letters were learned more rapidly than a list of 16 three-letter words. Therefore, in the major experiment, the Ss were given all appropriate elements on test trials so that only associative learning was required. Increases in formal similarity caused decreases in rate of learning for both types of lists, and the mechanisms of the interference seemed to be the same for both types of lists, However, the learning of the trigram lists was more rapid than the learning of the triad lists, the difference being maximal with low similarity.