Integration and representation in rats' serial pattern learning in the T-maze

Rats were exposed to three-trial series consisting of reinforced (R) trials and one nonreinforced (N) trial in a fixed order, RRN and RNR (Experiments 1 and 2) or NRR and RRN (Experiment 3), on extended visually distinct runways in a T-maze. When initially presented with the same sequence on each series in a session (separate presentations) with the same runway on all trials within a series (Experiments 1 and 3), all the rats developed slower running speeds on N than on R trials. When a runway was sometimes changed between the first and next two trials during separate presentations training (Experiment 2) or both sequences were later intermixed within each session in each experiment, only rats exposed to each sequence on a specific runway maintained these serial running patterns. Rats displayed serial running patterns on a test RNN sequence similar to that on the RNR sequence (Experiment 2), as would be predicted by an intertrial association model of serial pattern learning (Capaldi & Molina, 1979), but responded on test RRR and NRN sequences (Experiment 3) as would be predicted by an ordinal-trial-tag/intratrial association model (Burns, Wiley, & Payne, 1986). Results from test series of free-choice trials in Experiments 1 and 2 failed to support a prediction of the intratrial association model that these rats would integrate RRN and RNR sequences. Rather than always selecting a baited runway on both the second and the third free-choice trials, the rats only selected a baited runway on the third trial on the basis of their choice on the second trial, as would be predicted by the intertrial association model. Only after experiencing all possible outcome sequences during forced-choice training in Experiment 3 did these rats predominantly select a baited runway on every free-choice trial.     

Susceptibility to interference effects in short-term memory of normal and retarded readers.

The short-term memory for serial order of third and fourth grade normal and retarded readres (Ns = 13) was studied. Six pictures of common objects were spatially presented and subjects were required to reconstruct the sequence. On the first six trials, the same pictures were repeatedly presented in different sequences. On the seventh trial, a new set of stimuli was introduced. Analysis of short-term memory over trials showed that normal and retarded readers were similar on Trial 1 but the performance of retarded readers deteriorated more over trials than the performance of normal readers. Short-term memory of both groups improved on Trial 7. The results indicate a greater susceptibility to interference in the short-term memory of retarded readers.     

Higher Order Chunking in Serial Pattern Learning by Rats in the T-Maze

Rats were repeatedly exposed to two- and three-trial series consisting of different reinforced (R) and nonreinforced (N) trials in a fixed order on extended visually distinct runways in a T-maze. When initially presented with the same sequence, RR or RN in Experiment 1 and RRN or RNR in Experiment 2, on each series in a session (Separate Presentations), rats developed slower running speeds or bypassed the runway in returning to the start chamber on N more than on R trials. These serial response patterns occurred whether rats experienced each sequence on a specific runway (Associated group) or equally on different runways over sessions (Nonassociated group). When sequences were intermixed within each session, only the Associated group maintained its serial pattern responses to both sequences while the Nonassociated group only did so within the RRN sequence. When allowed to choose between runways over trials, the Associated group tended to select the runway associated with the RR sequence on the first two free-choice trials while rats in the Nonassociated group tended to alternate their choices of runways. Switching the relevancy of the runway context in the second experiment caused rats in each group to react like rats in the other group on forced-choice trials. In terms of Capaldi's (1992) model of levels of chunking in serial pattern learning, our findings indicate that rats learned to anticipate at least second trial outcomes by using higher order list or contextually cued chunking and also to anticipate third trial outcomes by using lower order series chunking.     

Save the last dance II: unwanted serial position effects in figure skating judgments

Serial position effects may occur whenever options are judged in sequence, as is the case in figure skating competitions. International figure skating competitions consist of at least two rounds, with serial position being randomized in the first round. Figure skaters with better scores in the first round perform later in the second round. Despite the initial randomization of serial position, figure skaters who perform later in the first round receive better scores in first and in the second round. The findings presented here replicate those of Bruine de Bruin (2005) [Save the last dance for me: unwanted serial position effects in jury evaluations. Acta Psychologica, 118, 245-260], using a larger dataset, and addressing potential concerns about Bruine de Bruin's analyses.     

Do updating tasks involve updating? Evidence from comparisons with immediate serial recall

Updating tasks require participants to process a sequence of items, varying in length, and afterwards to remember only a fixed number of the elements of the sequence; the assumption being that participants actively update the to-be-recalled list as presentation progresses. However recent evidence has cast doubt on this assumption, and the present study examined the strategies that participants employ in such tasks by comparing the serial position curves found in verbal and visuo-spatial updating tasks with those seen in standard serial recall tasks. These comparisons showed that even when the same number of items are presented or recalled, participants perform less well in an updating than a serial recall context. In addition, while standard serial position effects were observed for serial recall, marked recency and reduced or absent primacy effects were seen in updating conditions. These findings suggest that participants do not typically adopt a strategy of actively updating the memory list in updating tasks, but instead tend to wait passively until the list ends before trying to recall the most recently presented items.     

Do updating tasks involve updating? Evidence from comparisons with immediate serial recall

Updating tasks require participants to process a sequence of items, varying in length, and afterwards to remember only a fixed number of the elements of the sequence; the assumption being that participants actively update the to-be-recalled list as presentation progresses. However recent evidence has cast doubt on this assumption, and the present study examined the strategies that participants employ in such tasks by comparing the serial position curves found in verbal and visuo-spatial updating tasks with those seen in standard serial recall tasks. These comparisons showed that even when the same number of items are presented or recalled, participants perform less well in an updating than a serial recall context. In addition, while standard serial position effects were observed for serial recall, marked recency and reduced or absent primacy effects were seen in updating conditions. These findings suggest that participants do not typically adopt a strategy of actively updating the memory list in updating tasks, but instead tend to wait passively until the list ends before trying to recall the most recently presented items.     

Two types of serial dependence in visual working memory

Stimulus representations in working memory depend on memory traces of past stimuli both from previous trials and from the current trial. However, it is unclear whether the same or different mechanisms underlie this serial dependence across and within trials. We directly contrasted estimates of bias for pairs of immediately successive stimuli across and within trials. In each trial, participants memorized two consecutive motion direction stimuli (S1 and S2) and after a short delay were cued to report one of them. We found serial dependence across trials: The current S1 was attracted towards the preceding S2 when the latter had been cued for report. In contrast, within the same trial S2 was repulsed from S1. In addition, repulsion within a trial occurred for a broader range of motion direction differences between stimuli than attraction across trials. A second experiment in which 25% of trials did not require a response demonstrated that across‐trial attraction did not depend on whether the previous S2 actually had to be reported. Our findings provide evidence for two types of serial dependence operating across and within trials. They support the notion of different mechanisms integrating or segregating current from similar past memory contents depending on their task relevance.     

Rule learning in rats: serial tracking in interleaved patterns

Humans have the ability to chunk together information from nonadjacent serial positions in sequential patterns. For example, human subjects can extrapolate the pattern, A-M-B-N-C-O-D-P-E-..., to find the missing element, Q, by sorting pattern elements into two component interleaved subpatterns: A-B-C-D-E and M-N-O-P-... Two experiments investigated the ability of rats to reorganize pattern elements from nonadjacent serial positions into chunks not presented by the experimenter. Rats learned either a structured or unstructured sequence interleaved with elements of a repeating sequence (experiment 1) or an alternation sequence (experiment 2). In both experiments, rats learned the interleaved subpatterns at different rates. Acquisition rate was correlated with the structural properties of component subpatterns and the nature of the rules required to describe the interleaved subpatterns. The results indicate that rats are sensitive to the organization of nonadjacent elements in serial patterns and that they can detect and sort structural relationships in interleaved patterns. Received: 7 September 1998 / Accepted after revision: 27 January 1999     

Ordinal Position Learning and Remote Anticipation

Rats were runway trained on each of two 3-trial series of reward outcomes. The series are labeled XNY and ZNN, for which X represents a trial that was rewarded with Noyes pellets and N represents a trial that ended with no reward. Units of distinctively flavored breakfast cereals served as reward on trials labeled Y and Z. One group (Floor) had each series occur with a correlated runway floor, either smooth and black or rough and white. For a second group (Memory), the floor cue was uncorrelated with series. Animals in both groups learned to approach the goal rapidly on the 1st trials of the 2 series and slowly on the 2nd trials, but only Group Floor learned to differentiate the 3rd trials of the series. These results recommend a view of serial learning that emphasizes the role played by information about the ordinal position of series items.     

Ordinal position learning and remote anticipation

Rats were runway trained on each of two 3-trial series of reward outcomes. The series are labeled XNY and ZNN, for which X represents a trial that was rewarded with Noyes pellets and N represents a trial that ended with no reward. Units of distinctively flavored breakfast cereals served as reward on trials labeled Y and Z. One group (Floor) had each series occur with a correlated runway floor, either smooth and black or rough and white. For a second group (Memory), the floor cue was uncorrelated with series. Animals in both groups learned to approach the goal rapidly on the 1st trials of the 2 series and slowly on the 2nd trials, but only Group Floor learned to differentiate the 3rd trials of the series. These results recommend a view of serial learning that emphasizes the role played by information about the ordinal position of series items.     

French‐learning toddlers use gender information on determiners during word recognition

In gender‐marking languages, the gender of the noun determines the form of the preceding article. In this study, we examined whether French‐learning toddlers use gender‐marking information on determiners to recognize words. In a split‐screen preferential looking experiment, 25‐month‐olds were presented with picture pairs that referred to nouns with either the same or different genders. The target word in the auditory instruction was preceded either by the correct or incorrect gender‐marked definite article. Toddlers’ looking times to target shortly after article onset demonstrated that target words were processed most efficiently in different‐gender grammatical trials. While target processing in same‐gender grammatical trials recovered in the subsequent time window, ungrammatical articles continued to affect processing efficiency until much later in the trial. These results indicate that by 25 months of age, French‐learning toddlers use gender information on determiners when comprehending subsequent nouns.     

Timeout as a reinforcer for errors in a serial position task

After learning to press keys in a predetermined serial position sequence, with timeouts scheduled as a consequence of errors, monkeys developed stereotyped errors. As soon as a new trial started, the animals would make an error. On trial after trial, they pressed the same incorrect key at the first member of the sequence, even though they had previously learned the sequence. First-member errors occurred even when sequences of fully bright keys marking correct choices were presented. When timeout was eliminated as a consequence of one first-member error, subjects switched to an error that did produce the timeout. When all first-member errors failed to produce timeout the monkeys ceased responding. Both prefeeding and reduction in reinforcement density resulted in stereotyped errors occurring earlier in the session.     

Sequential search processes in long-term memory

In an experiment employing the symbol-element recognition task (Mohs, Wescourt, & Atkinson, 1975), subjects first learned six lists consisting of four words (elements) each. Each list was associated with a unique consonant (symbol). Subsequently, on each of a series of test trials, subjects were presented with one, two, or four symbol-element pairs. A positive response was required if all test words were correctly paired with their associated consonants and a negative response if any one test word was incorrectly paired with a consonant. Of primary concern was the way reaction time (RT) varied with number of pairs presented, the type of response required, and, on negative trials, the position of the mismatched pair in the test display. RT increased with the number of pairs presented on a trial and the increase was greater for positive than for negative trials. For negative pair trials, RT increased with the distance of the mismatched pair from the top of the test display. On negative trials in which the top pair in the test display was the mismatched pair, RT increased with the total number of pairs presented on the trial. A serial, probabilistic order of processing model is proposed to account for these results, and applications of the model to other paradigms are discussed.     

The role of timing deviations and target position uncertainty on temporal attending in a serial auditory pitch discrimination task

Listeners were presented with sequences of tones that ascended in semitone intervals. On each trial a single target tone in the sequence was displaced in pitch, and listeners were required to indicate whether the target tone was higher or lower than its normal pitch. Task constraints, specifically target serial position uncertainty and the probabilistic relationship between time deviations and target tones, were varied in order to determine the impact of task constraints on temporal attending strategy. When listeners had no advance knowledge of the serial position of the target, and early and late targets provided information regarding target serial position, performance was better for early and late target trials than for on-time target trials (Experiment 1). When listeners had no advance knowledge of the serial position of the target, and early and late temporal deviations provided no information regarding target serial position, performance for late target trials was superior to that for early and on-time target trials (Experiment 2). Finally, when target serial position uncertainty was eliminated, performance was equivalent across all three levels of target timing (early, on time, late). The results indicate that performance profiles based on stimulus timing properties are affected by various task constraints as well as by stimulus properties.     

Gaze behavior of trampoline gymnasts during a back tuck somersault

In trampolining, gymnasts perform a variety of rotational jumping elements and have to demonstrate perfect control of the body during the flying phase. The performance of a somersault should include an opening phase, i.e. the legs are fully extended pointing vertically at 180° called “kick-out”. As previous studies have shown, gaze behavior is essential for the controlling during the flight phase and to prepare for a perfect landing. Gymnasts supposedly use the trampoline bed as orientation and differences in gaze behavior can be expected, depending on how a somersault is performed. The present study investigates the gaze behavior of gymnasts during a back tuck somersault on the trampoline. Eleven experienced trampoline gymnasts performed back tuck somersaults with and without a kick-out while wearing a light weight portable eye-tracking device. All subjects fixated their gaze on a specific point at the trampoline bed and thus used visual information to prepare for landing. During the period of fixation, gymnasts' eyes moved continuously downwards to counteract the backwards head movement. The point of fixation differed between each somersault. Apparently, the fixation position depended on the gymnast's landing position in the bed. Performing a somersault with a kick-out allows gymnasts to orient themselves earlier and thus prepare sooner for landing. Unexpectedly, gymnasts of a higher performance class fixated the bed later compared to less experienced athletes. Supposedly, gymnasts of a better class can allow themselves to fixate later in order to optimize the form and execution of a somersault.     

Rehearsal strategy as a function of recall expectation

The subjects were divided into three groups with respect to their expectations concerning a recall task given after the final trial of the usual STM distractor procedure. Group 1 were told only that they would have to recall during each trial's recall interval, thus did not expect to have to recall again. Group 2 were told that they would have to recall all the words presented in the experiment at the end of the last trial, in addition to the trial-by-trial recall. Group 3 were told only that they would have to recall after all words had been presented and they sat passively through the presentation trials. In addition to their recall expectations, half of the subjects in each group received a 2-s presentation and half received a 5-s presentation interval. It was found that the length of the presentation interval had an effect on the number of words recalled at the end of all trials, but recall expectancy did not. However, expectancy did determine the rehearsal strategies of subjects and hence the serial positions from which items were recalled.     

Temporal and interactional effects in short-term storage

The operation of temporal and interactional processes in short-term storage was studied under conditions which require that information about all items presented be stored and the relative retention of all be evaluated concurrently, but preclude further interference after presentation by testing or retrieval effects. Random sequences of twelve two digit numbers from a known set of thirteen were presented visually at 1, 2, or 4 per sec. for full interval and .25 sec. presentation durations to 15 Ss who reported the missing number that was not presented from the set. For 1/sec. full duration presentations the missing scan serial position error distribution shows a linear decrease in errors from first through last presented items. As rate of presentation increases there is a linear increase in total errors, a linearly increasing primacy effect, and an increase of errors over at least the last half of the sequence such that the error distribution remains linear with the same slope. These findings are compatible with the operation of time dependent interactional and perceptual processes in short-term storage but not with autonomous decay.     

Gaze,head and eye movements during somersaults with full twists

Somersaults with or without twists are the most important elements in sports such as gymnastics or trampolining. Moreover, to perform elements with the highest possible difficulty gymnasts should show good form and execution during the flight phase. In order to ensure perfect body control and a safe landing, gaze behavior has been proven to be crucial for athletes to orientate in the air. As eye movement and head movement are closely coordinated, both must be examined while investigating gaze behavior. The aim of the current study is to analyze athletes' head motion and gaze behavior during somersaults with full twists. 15 skilled trampoline gymnasts performed back straight somersaults with a full twist (back full) on the trampoline. Eye movement and head movement were recorded using a portable eye-tracking device and a motion capture suit. The results indicate that gymnasts use the trampoline bed as a fixation point for orientation and control the back full, whereas the fixation onsets for athletes of a better performance class occur significantly later. A strong coordination between gymnasts' eye movement and head movement could be determined: stabilizing the gaze during the fixation period, the eyes move in combination with the head against the twisted somersault direction to counteract the whole body rotation. Although no significant differences could be found between the performance classes with regard to the maximum axial head rotations and maximum head extensions, there seems to be a trend that less skilled gymnasts need orientation as early as possible resulting in greater head rotation angles but a poorer execution.     

Primacy, recency, and suffix effects in auditory short-term memory for pure tones: evidence from a probe recognition paradigm.

The present study was designed to explore serial position and suffix effects in the short-term retention of nonverbal sounds. In contrast with previous studies of these effects, a probe recognition paradigm was used to minimize the possibility that participants would use a verbal labelling strategy. On each trial, participants heard a memory set consisting of three pure tones, followed five seconds later by a probe tone. Participants were required to indicate whether or not the probe tone had been a member of the memory set. On most trials, a suffix sound was presented 1 second following the third sound in the memory set. Results revealed that tones presented in the first and last positions of the memory set were recognized more accurately than were tones presented in the middle position. Furthermore, recognition of sounds presented in the last position was compromised when the memory set was followed by a postlist suffix of similar pitch, spectral composition, and spatial location.     

The futility of explicit knowledge of a sequence of tasks

In an experiment that combined the task-shifting methodology with a serial reaction-time task, three groups of participants had to shift among a set of four tasks that were arranged in regular sequences of length eight. Two groups of participants were given explicit knowledge about the sequence of tasks. To ensure that the knowledge of the sequence was referred to in each trial, one group was asked to verbalise the forthcoming task (verbalisation group), whereas the other group had to detect trials that deviated from the learned sequence (detection group). Participants of a control group were given no information about the sequence of tasks. In addition, for all experimental groups in half of the blocks of trials external precues were presented which indicated the forthcoming task. The control group exhibited substantial task-shifting costs that were greatly reduced by the presentation of precues. Participants of the explicit-knowledge groups showed no indication that explicit knowledge resulted in advance preparation of the forthcoming task. In addition, the effect of the precues depended on the secondary task that had to be performed on the basis of explicit knowledge. Whereas for the detection group precues reduced shift costs to the same degree as for the control group, the verbalisation group showed no precueing benefits at all.