Contextual interference effects in sequence learning for young and older adults

Practice of different tasks in a random order induces better retention than practicing them in a blocked order, a phenomenon known as the contextual interference (CI) effect. Our purpose was to investigate whether the CI effect exists in sequence learning, such that practicing different sequences in a random order will result in better learning of sequences than practicing them in blocks, and whether this effect is affected by aging. Subjects practiced a serial reaction time task where a set of three 4-element sequences were arranged in blocks or in a random order on 2 successive days. Subjects were divided into 4 groups based on a 2-GROUP (young or old) by 2-ORDER (random or blocked practice) between-subject design. Three days after practice (Day 5), subjects were tested with practiced and novel sequences to evaluate sequence-specific learning. The results replicate the CI effect in sequence learning in both young and older adults. Older adults retained sequences better when trained in a random condition than in a blocked condition, although the random condition incurs greater task switching costs in older adults during practice. Our study underscores the distinction between age-related effects on learning vs. performance, and offers practical implications for enhancing skill learning in older adults.     

Contextual adjustments in cognitive control across tasks

Does encountering information-processing conflict recruit general mechanisms of cognitive control or change only the representations of specific cues and responses? In the present experiments, a flanker task elicited responses to symbolic information (arrow meaning), whereas Stroop-like tasks elicited responses to nonsymbolic information (color of a letter or location of a target box). Despite these differences, when participants performed the flanker and Stroop tasks intermittently in randomized orders, the extent of information-processing conflict encountered on a particular trial modulated performance on the following trial. On across-task trial pairs, increases in response time to incongruent relative to congruent stimulus arrays were smaller immediately following incongruent trials than immediately following congruent trials. The degree of cognitive control exerted on a particular task thus appears to reflect not only the quality, but also the quantity, of recent experiences of information-processing conflict.     

Contextual interference effects on the acquisition and retention of fundamental motor skills

This study was designed to examine the effect of three practice models (repetitions, random, and combined) on the acquisition and retention of fundamental motor skills. 54 girls in Grade 4 were randomly assigned to the three different practice groups who practiced three skills of ball rolling, racket striking, and ball kicking. All subjects received pretests posttests, and a 3-wk, retention test. Performance was significantly improved during practice in the three groups for the three skills. The repetitions group performed better than the other two groups at the end of practice. The contextual interference effect in retention was only shown for the racket-striking skill, in which the random group was significantly better than the repetitions and the combined groups. An attempt was made to attribute that specific result to the special characteristics of the striking skill in this study as an open skill with which subjects had a previous experience.     

Contextual interference in learning precision skills

This research studied the effect of different organisations of practice (blocked and random) on the learning of three different types of throwing. 35 male students practiced three precise throws for 3 wk. Initially the subjects were separated into two groups who trained under different conditions of practice (blocked and random). All subjects improved significantly from initial performance, with both blocked practice and random practice. At the end of acquisition no differences were found between the groups. No significant differences were found on retention tests carried out 48 hr., 4 wk., and 8 wk. after the training period.     

Contextual interference: a meta-analytic study

A meta-analysis of the contextual interference effect produced 139 estimates of effect sizes from 61 studies. The average overall effect size was .38. The effect size for basic research (.57) was significantly different from applied research (.19). Significant differences were also obtained between the effect sizes for adults (.50) and those for younger learners (.10). Power for retention and transfer scores was not significantly different. The overall mean power of the studies reviewed was .43.     

Locus of semantic interference in picture-word interference tasks

Picture#x2014;word interference studies typically show that semantically related distractor words embedded within a picture slow picture-naming responses, relative to unrelated ones. This semantic interference effect is commonly interpreted as arising from the competition of lexical#x2014;semantic (e.g., Schriefers, Meyer, & Levelt, 1990) or lexical#x2014;phonological (e.g., Starreveld & La Heij, 1996) codes. The experiment reported here tests a crucial assumption shared by these accounts#x2014;namely, that the effect reflects a lexical, rather than a nonverbal, conceptual conflict. Pictures were named while participants attempted to ignore embedded distractors that were in either verbal or pictorial format. The presence of both words and pictures substantially interfered with naming responses, but only words, not pictures, were found to induce semantic interference. These findings support the claim that for semantic interference to arise, both target picture and distractor have to be lexicalized. Consequently, a general conceptual locus of the effect can be excluded, and the claim that semantic interference is based on a lexical conflict is confirmed.     

Response interference in compatibility tasks

Affective priming (AP) is a well-established phenomenon in which performance to a valenced target is typically better when it is preceded by an affectively congruent prime than when it is preceded by an incongruent prime. Several studies have emphasized a strong similarity between AP and Stroop suggesting that both are driven by response interference. The present study investigated this hypothesis by testing whether a general prediction of the response interference model was verified in the two tasks. This prediction refers to target strength and states that the size of compatibility effects should increase as the strength of the relevant information decreases. In four experiments, we show that this general prediction of the response interference model was verified in AP and Stroop when the strength of the relevant information was manipulated at the perceptual level (Experiments 1 and 2), while the opposite pattern was observed when this variable was manipulated at the semantic level (Experiments 3 and 4). While the results do not undermine the hypothesis that AP and Stroop effects are governed by response interference, they suggest that the model should be refined in order to account for differential effects of target strength in compatibility tasks.     

Sex differences and practice effects on two visual-spatial tasks

Sex differences on visual-spatial tasks have been assumed to be present in young children, and performance on visual-spatial tasks has been assumed to be resistant to modification. Third and fifth graders were pretested on embedded and successive figures. Half of the 110 children then received limited feedback after which both groups were posttested. Grade, time of testing, and type of task significantly affected visual-spatial performance. Additional study might indicate whether amount of practice influences final level of performance for girls and boys and the asymptote on visual-spatial tasks is similar.     

Contextual cueing reduces interference from task-irrelevant onset distractors

Three experiments were conducted to examine the interaction of top-down and bottom-up influences on visual search. More specifically, we examined the extent to which stimulus-driven capture of attention by abrupt onset distractors would disrupt the acquisition and expression of memory-based guidance of attention as exemplified by the contextual cueing effect (Chun & Jiang, 1998, 1999). In Experiment 1 onset distractors were introduced at the beginning of practice on the search task. Results indicated that onset distractors and repeated distractor patterns had independent and opposing influences on the efficiency of search. Experiment 2 ruled out an alternative hypothesis concerning the capture of attention by abrupt onsets. In Experiment 3, abrupt onset distractors were introduced following several hundred trials of practice with repeated and new distractor patterns in visual search. In this case contextual cueing observed in the repeated distractor configuration condition partially suppressed the detrimental influence of the abrupt onset distractors on search performance. These data are discussed in terms of the interaction of top-down and bottom-up influences on visual search.     

Contextual interference in implicit and explicit motor learning

The purposes of this study were to examine the contextual interference effect in implicit learning and to compare implicit and explicit learning. Thirty-two participants performed a pursuit-tracking task for 60 acquisition and ten retention trials. The middle segment of target pathways had only two patterns whereas other segments had random patterns. A combination of awareness and practice order for the middle segment created four acquisition conditions: implicit-blocked, implicit-serial, explicit-blocked and explicit-serial. A questionnaire and a recognition test revealed that implicit groups were unaware of the repetition. Results showed no contextual interference effect in either implicit or explicit learning. Acquisition and retention performances were better for the middle segment than the other segments regardless of awareness. No difference between the implicit and explicit groups was found, suggesting that the implicit learning condition led to learning equivalent to the explicit learning condition.     

Comparison of two oddity tasks with pigeons

Two oddity tasks were compared: one in which the odd stimulus could appear on any of the three stimulus positions (true oddity); the other in which the odd stimulus could only appear on the left or right but not the center (oddity-from-sample). A stimulus-configuration theory predicts faster oddity-from-sample learning, whereas a theory, based on shifts in observing over trials, predicts faster learning of true oddity. Pigeons learned the oddity-from-sample task faster, thus supporting configuration theory. Performance on the oddity-from-sample task but not the true oddity task was facilitated by increasing the number of responses required to terminate a trial. When the oddity-from-sample pigeons were shifted to the true oddity task, no evidence of positive transfer was found, suggesting that a configuration theory alone is insufficient to explain differences in acquisition. Only when a correction procedure was introduced did the true oddity pigeons perform above 50%.     

Contextual effects in vowel perception II: Evidence for two processing mechanisms

Recent experiments have indicated that contrast effects can be obtained with vowels by anchoring a test series with one of the endpoint vowels. These contextual effects cannot be attributed to feature detector fatigue or to the induction of an overt response bias. In the present studies, anchored ABX discrimination functions and signal detection analyses of identification data (before and after anchoring) for an [i]-[I] vowel series were used to demonstrate that [i] and [I] anchoring produce contrast effects by affecting different perceptual mechanisms. The effects of [i] anchoring were to increase within-[i] category sensitivity, while [I] anchoring shifted criterion placements. When vowels were placed in CVC syllables to reduce available auditory memory, there was a significant decrease in the size of the [I]-anchor contrast effects. The magnitude of the [i]-anchor effect was unaffected by the reduction in vowel information available in auditory memory. These results suggest that [i] and [I] anchors affect mechanisms at different levels of processing. The [i] anchoring results may reflect normalization processes in speech perception that operate at an early level of perceptual processing, while the [I] anchoring results represent changes in response criterion mediated by auditory memory for vowel information.     

The effects of interference tasks on recency in the free recall of action events

Summary Lists of verbal instructions were read aloud and each was enacted either by the subject (SPTs) or by the experimenter (EPTs). In Experiment 1 free recall was made of lists of SPTs and EPTs either immediately after presentation, after an empty 20-s delay interval, or after a 20-s delay interval filled with backward counting. The recall of recency items was unaffected by the empty delay interval, but was somewhat reduced by the counting task. In Experiment 2 free recall was made of lists of SPTs and EPTs either immediately after presentation or after a delay that was filled with a single SPT or a single EPT, 20 s in length. The recency effect evident in the immediate-recall condition was virtually wiped out in the delay conditions, irrespective of whether the delay task matched those in the free-recall list or not. These results are discussed in terms of the mnemonic similarity of the two types of action event.     

Contextual interference processing during fast categorisations of facial expressions

We examined interference effects of emotionally associated background colours during fast valence categorisations of negative, neutral and positive expressions. According to implicitly learned colour–emotion associations, facial expressions were presented with colours that either matched the valence of these expressions or not. Experiment 1 included infrequent non-matching trials and Experiment 2 a balanced ratio of matching and non-matching trials. Besides general modulatory effects of contextual features on the processing of facial expressions, we found differential effects depending on the valance of target facial expressions. Whereas performance accuracy was mainly affected for neutral expressions, performance speed was specifically modulated by emotional expressions indicating some susceptibility of emotional expressions to contextual features. Experiment 3 used two further colour–emotion combinations, but revealed only marginal interference effects most likely due to missing colour–emotion associations. The results are discussed with respect to inherent processing demands of emotional and neutral expressions and their susceptibility to contextual interference.     

Contextual interference processing during fast categorisations of facial expressions

We examined interference effects of emotionally associated background colours during fast valence categorisations of negative, neutral and positive expressions. According to implicitly learned colour-emotion associations, facial expressions were presented with colours that either matched the valence of these expressions or not. Experiment 1 included infrequent non-matching trials and Experiment 2 a balanced ratio of matching and non-matching trials. Besides general modulatory effects of contextual features on the processing of facial expressions, we found differential effects depending on the valance of target facial expressions. Whereas performance accuracy was mainly affected for neutral expressions, performance speed was specifically modulated by emotional expressions indicating some susceptibility of emotional expressions to contextual features. Experiment 3 used two further colour-emotion combinations, but revealed only marginal interference effects most likely due to missing colour-emotion associations. The results are discussed with respect to inherent processing demands of emotional and neutral expressions and their susceptibility to contextual interference.     

Contextual interference in movements of the same class: differential effects on program and parameter learning

Contextual interference effects in motor learning usually were not found when the tasks to be learned presumably required the same generalized motor program (GMP) and differed only with regard to the movement parameters (see Lee, Wulf, & Schmidt, 1992; Magill & Hall, 1990). Thus, tasks requiring different motor programs (e.g., different relative timings) seemed to be a prerequisite for random practice to be more effective than blocked practice. However, the previous studies (that did not find random/blocked differences) used global error measures that confounded errors in relative timing and errors in absolute timing. In the present study, subjects practiced three movement patterns that had the same relative timing (requiring the same GMP) but different overall durations (requiring different parameters). Errors in relative timing and in absolute timing were assessed separately. The results indicate that random practice is more effective for the learning of relative timing (GMP learning) and less effective for the learning of absolute timing (parameter learning) than blocked practice. Preliminary ideas as to the reasons for this effect are discussed.     

Assessing the age-related effects of proactive interference on working memory tasks using the Rasch model

Inhibition-reduction theory (L. Hasher & R. Zacks, 1988) hypothesizes that the age-related decline in working memory (WM) span is a result of a decrease in the ability to inhibit irrelevant information in WM. Using the Rasch psychometric model, this study found that later trials on 2 WM span tasks were more difficult for older adults than for younger adults, consistent with inhibition-reduction theory's hypothesis that older adults are more susceptible to the effects of proactive interference (PI). Furthermore, after accounting for differential susceptibility to the effects of PI, age-related variance in WM span was reduced by about half. These results suggest that differential susceptibility to PI may account for a substantial portion, although not all, of the age-related decline in WM span.     

Contextual effects in duration experience

The role of contextual factors on duration estimates was investigated, employing 6 time intervals ranging from 15 to 35 sec (demarcated by the onset and termination of a display panel of lights). When compared with earlier research, the results suggest that duration estimates are affected by the context of the stimulus intervals with regard to other stimuli in the series. Specifically, those stimuli that were overestimated when they were the shortest members of the series were underestimated when they were the longest intervals of the stimulus series. In addition, a lengthening effect was observed: duration estimates increased over blocks of trials for all stimulus intervals.     

Contextual effects on number-time interaction

Time perception has long been known to be affected by numerical representations. Recent studies further demonstrate that when participants estimate the duration of Arabic numbers, number magnitude, though task-irrelevant, biases duration judgment to produce underestimation for smaller numbers and overestimation for larger numbers. Such effects were found in the present study to be significantly reduced when a weight unit gram was suffixed to the numbers rendering the mental magnitude differences between different numbers less distinctive. The effects were enhanced when a different unit kilogram was suffixed to the numbers enlarging the perceived magnitude differences between different numbers. The results indicate that effects of number magnitude on duration estimation should not be attributed to the mathematical differences between numbers but to how the numbers are perceived to differ from each other in magnitude in specific contexts when they denote concrete items. The results also provide new evidence for the theoretical proposal of a common generalized magnitude system and indicate that the system must be extended to include other action-oriented magnitudes, such as weight.     

Contextual interference effect on acquisition and retention of pistol-shooting skills

The effects of contextual interference on learning pistol-shooting skills in a natural training environment were examined. The shooting skills consisted of three "stages" with different requirements for the skill variations commonly used in the field. 12 participants were randomly assigned into one of two practice conditions, blocked vs serial. Following a 20-min. safety and skill instructional session, Blocked group practiced 10 trials in a row at each stage, while Serial group performed 5 trials in a row for each of the three stages and then repeated the cycle. Both groups completed a total of 30 practice trials over the three stages. A 10-min. rest interval was provided prior to a retention test which included 9 trials (3 trials at each stage in a blocked format). Results based on the data of Stage III, the most complex skill among the three stages, showed a pattern consistent with previous findings that practicing in the serial schedule depressed performance during initial training but maintained the performance better at retention, relative to the blocked practice.