Three-item List Research Articles

A Comparison of Sequential Learning Errors Made by Apes and Monkeys Reveals Individual but not Species Differences in Learning

Using methods comparable to those used previously to test closely-related taxa (Pan troglodytes and Macaca mulatta), our aim was to better understand how gorillas (Gorilla gorilla gorilla) and Japanese macaques (M. fuscata) learn sequences. Using a disappearing-type simultaneous chain, we trained five gorillas and eight macaques on a two-item list of colored stimuli presented via touchscreens. There was no difference across species in the number of trials required to learn the two-item list. We added a third item to the list as each subject reached criterion. We then analyzed the subjects’ first 30 trials with the three-item list and found that the rate of successfully sequencing the list varied by subject but not by species. In their first 30 trials of the three-item list, subjects selected the second item correctly only at chance, suggesting they had only encoded the first symbol when learning the two-item list. One gorilla, tested on longer sequences, showed similar responses: when first presented with a newly-lengthened list, he only selected the penultimate item at chance levels. Thus, the primates’ errors with newly-lengthened lists is suggestive of the chaining theory of learning. These results highlight similarities in list learning of these two distantly-related primate species as well as the clear intra-species variation in learning.

Pigeons (Columba livia) learn a four-item list by trial and error.

The aim of the current study was to assess whether pigeons could acquire a four-item list by trial and error. Pigeons received either extensive list training prior to being tested on a novel four-item list (i.e., the full-training group) or very limited training (i.e., the limited-training group). Specifically, subjects in the full-training group were trained to acquire a large set of two-item lists by trial and error, then a large set of three-item lists, and finally a large set of four-item lists. In addition, within each set, the number of training phases was gradually reduced. In contrast, the limited-training group were trained on a single four-item list prior to testing. Only one of the eight subjects (12.5%) in the limited-training group learned the novel four-item list. In contrast, all five subjects (100%) in the full-training group learned the novel four-item list. We suggest that the difference between groups reflects the fact that subjects in the full-training group acquired a learning set over the course of their extensive training. The current study is the first to demonstrate pigeons can learn a four-item list without phased training. (PsycINFO Database Record

A positional coding mechanism in pigeons after learning multiple three-item lists

Pigeons were trained on three three-item lists (List 1: A(1) --> B(1) --> C(1;) List 2: A(2) --> B(2) --> C(2;) List 3: A(3) --> B(3) --> C(3)). After sessions in which any one of the three lists could be presented on a trial, derived-maintained list and derived-changed list probe trials were introduced. The derived list probe trials were composed of three items, one drawn from each of the training lists. On derived-maintained probe trials, each item was in the same ordinal position it occupied during training (e.g., A(3) --> B(1) --> C(2)). On derived-changed probe trials, items that occupied the second and third position during training were exchanged (e.g., A(2) --> C(3) --> B(1)). The performance of subjects on derived-maintained probe trials was significantly above chance and no different to that observed on the training lists. In contrast, subjects' performance on derived-changed probe trials was significantly below chance. To our knowledge, this is the first study that has demonstrated pigeons are able to learn and retain multiple three-item lists. In addition, subjects' performance on the derived-maintained probe trials suggests that they acquire knowledge of each list item's ordinal position when learning multiple lists.

Memory Processing of a Serial List by Young Infants

Serial list learning is thought to be beyond the capabilities of infants before the end of their 1st year. In separate experiments with 3- and 6-month-olds, we studied infants' memory for a serial list using a modified serial probe recognition procedure that was originally developed for monkeys and a precuing procedure that was previously used with human adults. Infants were trained with a three-item list. One day later, they were precued with one list member and tested for recognition of another. When the precue specified valid order information, infants of both ages recognized the test item; when the precue specified invalid order information, infants of neither age did. These findings reveal that even very young infants can learn and remember the order of items on a serial list.

Recall of three-item sequences by pigeons

Pigeons were trained to recall an arbitrary sequence on a delayed matching-to-successive-samples (DMTSS) task. Sample items were presented successively and then displayed simultaneously. Subjects were required to respond to them in the order in which they appeared. In Experiment 1, pigeons responded correctly on 75% of the trials on a two-item DMTSS task but at a chance level of accuracy on a three-item task. In Experiment 2, pigeons who learned to produce a three-item sequence prior to DMTSS training mastered a three-item DMTSS task at a 75% level of accuracy. Control groups, trained initially with the same items on nonserial tasks, performed as poorly on a three-item DMTSS task as the naive subjects of Experiment 1. It was hypothesized that pigeons that first learned to produce a three-item list were able to recall three-item samples in DMTSS because they had learned to represent three-item sequences.

Spatial list learning in black-capped chickadees

Black-capped chickadees (Parus atricapillus), a food-storing bird, were presented with three-item lists of unique spatial configurations. Each item consisted of one baited and three nonbaited feeders. Memory for the location of the hidden bait in each configuration was tested. Both primacy and recency effects were observed. The results from this use of a new species and procedure provide further evidence for the generality of serial position effects in animals.

On the difference between verbal and nonverbal behavior

Language theorists have often proposed lists of the defining properties of language. This account reviews some of these and offers as an alternative a three-item list consisting of instructional control, equivalence classes, and autoclitic processes.

Serial position effects in humans and animals: A reply to Gaffan

Gaffan (1983) argues that there is only weak evidence for Roberts and Kraemer's (1981) contention that the primacy effect may be a general characteristic of primate memory. He considers our conclusion in the larger context of his own research and points out that he has reported several failures to find a primacy effect in list memory experiments with monkeys. Our position clearly needs clarification. We considered our data and those of Sands and Wright (1980a, 1980b) in the still broader context of comparative research. We found it notable that researchers in different laboratories, using different species of monkeys, different stimuli, and different procedures, had been able to produce reliable primacy effects in monkeys. At the time our paper was written, no primacy effects had been found for retention of once-presented lists in pigeons (MacPhail, 1980; Shimp, 1976; Shimp & Moffitt, 1974), rats (Roberts & Smythe, 1979), or a dolphin (Thompson & Herman, 1977). Our intention, then, was to indicate that primacy effects were reliably demonstrable in human and nonhuman primates but had not been demonstrated in nonprimate species. It was not our intention to imply that primacy effects had been found in every list memory experiment done with monkeys, any more than we would claim that every list memory experiment with humans shows a primacy effect. Gaffan's claim that a primacy effect may be found in monkeys only under certain experimental conditions should be acknowledged, but it does not detract from the fact that production of a primacy effect now can be generalized from human to nonhuman primates. Given that a primacy effect now has been demonstrated under certain conditions with monkeys, we may entertain theoretical accounts of this effect. Gaffan (1983) advances the hypothesis that monkeys in the Roberts and Kraemer (1981) and Sands and Wright (1980a, 1980b) experiments attended more to the initial item of a list than to the following items and that the primacy effects they observed were a consequence of better memory for more highly attended items. The initial stimulus was attended to more strongly because a response was required to introduce this stimulus but not the remainder of the list. In his experiments, monkeys had to respond to produce each list item, and no primacy effects were found. It is suggested that item presentation contingent on a subject's response maintains attention and high retention for all items on a list. We too have considered the possible importance of attentional processes in the primacy effects seen in our monkeys, and we continue to do so. However, there are some problems with the position advocated by Gaffan (1983). Gaffan says nothing about the recencyeffect. Both Roberts and Kraemer (1981) and Sands and Wright (1980a, 1980b) found an increase in retention for items at the end of a list. Why should retention improve for terminal items (often to a level higher than that for the initial item) if all items beyond the first One are poorly attended? In the Roberts and Kraemer experiments, list lengths of three and six items were randomly intermixed, with twice as many six-item lists as three-item lists. Animals could not predict whether the third item presented in a list would be in the middle of a six-item list or at the end of a three-item list. Yet, the same item was poorly retained when tested as Position 3 in a sixitem list and better retained when tested as the final item of a three-item list. If this item was poorly attended to in both cases, why was it better remembered in the three-item list than in the six-itemlist? Finally, let us consider research with nonprimate species. Shimp (1976) required pigeons to peck a key designating the correct position of each item in a three-item list, and Roberts and Smythe (1979) required rats to enter each of the alleys that made up a seven-item list. Since animals responded to each item of the list in both cases, Gaffan's response-dependent attentional hypothesis suggests that consistently high retention should be found at all serial positions. Instead, marked declines in performance were seen from the ends of the lists to the beginnings. Although attentional processes certainly may be important in memory experiments, it seems unlikely that response-generated attention can account for the variety of serial position effects seen in monkeys and other animals. There seems to be substantial evidence that the position of items in a list exerts strong effects on retention when the presentation of items is both response dependent and response independent.

Short-term visual recognition memory in pigeons.

Recognition memory for lists of items was investigated in pigeons using a YES-NO recognition technique. Experiment I showed that increasing the exposure duration of the first item of a two-item list improved recognition for that item without impairing recognition of the second item. Experiment II showed that decreasing the inter-trial interval had no effect on correct YES responses but significantly increased the number of false YES responses. Experiment III showed that recognition for the last two items of a three-item list was no poorer than that for lists of only two items. Experiment IV showed that increasing the delay between presentation and test of a two-item list (from 0·25-1 s) had a more disruptive effect on recognition for the second than for the first item. The data from these four experiments support a model proposed by Roberts and Grant, according to which memory traces are independent, and decay as a negatively accelerated function of time. Experiments V, VI, and VII investigated recognition for lists of three, four, and five items, and found no evidence for a primacy effect, performance being a linear function of time since sample offset.

Memory processes in children with learning disabilities: Evidence for deficient rehearsal

The possibility that deficient rehearsal is responsible for poor learning in children with learning disabilities was examined by comparing single-trial immediate and delayed free recall of learning-disabled children and children with no such disability. The two groups were matched for sex, age (9–10 years), and IQ ( X approximately 100). In Experiment 1, 11 words were presented and recalled after delays of 0 to 120 sec.; the delay was either unfilled or filled by an irrelevant counting task. The results showed that in immediate free recall primacy was poorer in the learning-disabled group, but recency of both groups was similar. In delayed free recall both primacy and recency of the learning-disabled group were poorer. Counting reduced recall of both groups to the same relative degree. In Experiment 2, 3, 6, 9, or 12 words were presented and recalled immediately or after a 30-sec delay. In immediate recall of three-word lists, the two groups were similar. With longer lists, primacy of the learning-disabled group was lower than the nondisabled, but recency of both groups was similar. In delayed recall of three-item lists, learning-disabled children were poorer than nondisabled ones, and with longer lists both primacy and recency of learning-disabled children were lower. These results are consistent with the hypothesis that rehearsal and/or retrieval from long-term storage are deficient in children with learning disabilities.

Proactive inhibition of prompted items

Retention of three-item lists was measured after 15 sec of interpolated activity. Recall was either prompted by the first word of a list or it was not: lists were presented after a very short or after a relatively long intertrial interval. Data from Ss differing widely in age and educational background failed to support the hypothesis that prompted recall should result in less proactive inhibition than unprompted; proactive inhibition in short-term memory may accordingly represent a deficit in storage rather than retrieval.