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Learners (n=48) practiced three multisegment movements with distinct target movement times. Four practice groups were compared: blocked, random, and two groups who had a win-shift/lose-stay schedule (WSLS1 and WSLS2). For these latter groups switching between practice tasks was performance-contingent: within 5% of target time for 1 or 2 consecutive trials, respectively. During acquisition, blocked performance was more accurate than for both random and WSLS2 groups. The WSLS1 group performed between blocked and random groups, but did not differ from either. In a next-day retention test, the random group scored better than the blocked group. The WSLS1 group performed similarly to the random practice while the WSLS2 group's scores were similar to those of the blocked group. Results encourage further study of similar practice schedules.

To investigate the interference effect in volleyball players and nonathletes (ns=10) when they executed both saccadic and key-press reaction time (RT) tasks concurrently, the two groups responded to the onset of peripheral visual stimuli as quickly as possible in single and dual conditions. In the single condition, subjects responded with either saccadic eye or key-press movement. In the dual condition, they responded concurrently with both saccadic eye and key-press movements. In both groups, the key-press RT was longer in the dual condition than in the single condition. However, the amount of key-press RT delay was remarkably smaller for the volleyball players than for nonathletes. This suggests the motor command to initiate manual movement of volleyball players might be less interfered with by a concurrent oculomotor command to initiate saccadic eye movement when compared to that of nonathletes.

Duration of practice trial on a pursuit rotor task in contextual interference was investigated. Participants practiced at each of 4 angular velocities, with 24 participants completing 28 trials lasting 20 sec., and 24 participants completing 112 trials of 5 sec. Half of the participants in each trial-duration condition practiced in a blocked format and half practiced in a random format. After random practice posttest performance was better than blocked practice when practice-trial duration was 20 sec., but worse when practice-trial duration was 5 sec. This result is not consistent with theoretical explanations of the contextual interference effect and is discussed with reference to the task characteristics and demands of the pursuit rotor.

Predicted to diminish task performance were (a) distraction by telephone conversation and (b) older age. 38 participants pointed to letters on a randomized or alphabetized letter matrix during distraction by telephone conversation or no distraction. In a within-subjects design, telephone conversation negatively affected completion time but there were no age differences. Implications for cellular telephone use while driving are discussed.

Observers viewed a screen on which a number of patches containing horizontally moving pixels were presented. Target patches consisted of pixels whose motion simulated the rotation of a cylinder around its Y-axis; distractors, of pixels whose motion was linear. The task was to assess whether a display contained a target patch. Exp. 1 showed that the superposition of the displays with drifting sine-wave gratings interfered with rotation detection in a spatial- and temporal-frequency specific manner. In Exp. 2, dichoptic presentation greatly reduced the interference of the drifting gratings. It is argued on various grounds that the process(es) responsible for the detection and discrimination of rotating structure in depth exists at a low level of the visual system.

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.

On a digit-counting Stroop task, processing of the slower, nonverbal, i.e., number, dimension was slowed further by a large-number set (6 to 9), as compared with a small-number set (1 to 4). In the task, neutral symbols or conflicting digits were arranged on a horizontal line (e.g., @@@, 444) and on two separate sheets. Each sheet contained 120 stimulus arrays. Subjects counted out loud the number of symbols or digits in each array, and their counting times for each sheet were recorded. 23 subjects received the small-number set while 21 received the large-number set. It was found that counting a large number of symbols took significantly longer time (by 162 sec. per 120 stimulus arrays) than counting a small number of symbols. Moreover, interference was nonexistent (2 msec. per stimulus array) when a large number of conflicting digits were counted but was of a typical magnitude (110 msec. per stimulus array) when a small number of conflicting digits were counted. This suggests that Stroop interference is better explained as the result of comparable, not of differential, processing speeds of the two stimulus dimensions. Implications for the cause and the locus of Stroop interference are discussed.

The current investigation explored the influence of irrelevant stimuli on the standard Stroop color-word effect. Also investigated is the effectiveness of a new direction-related test which, unlike previous direction-related Stroop-like measures, exactly parallels format of the original Stroop in administration. This DirectionWord Test uses arrowheads at the ends of each target word to depict direction, e.g., left, right, and middle. 92 undergraduate students volunteered to participate. Analysis indicated that interference is found on the Color-Word Test, even with noncolor words as stimuli. Interference also occurred on the new Direction-Word Test. The correlation between the two forms of the Stroop effect was low, although significant, perhaps indicating there are different systems involved in response interference.

The present study modeled the relationship between the Stroop and the neutral naming times to investigate the mechanism underlying the Stroop interference effect. 95 subjects took six alternative versions of the Stroop task and the naming times in the Stroop and neutral conditions were each averaged across the tasks to arrive at a more general measure of the Stroop and neutral naming times. Regression analysis of these general measures indicated a linear function with a small and nonsignificant intercept and a slope significantly greater than one. This finding is consistent with Chen's 1996 results and supports the hypothesis that the mechanism underlying the Stroop interference is interactive or multiplicative rather than stage-like or additive and that a ratio of Stroop over neutral naming times was psychologically a more appropriate measure.

The present study investigated the generalizability of contextual interference effects by extending previous laboratory and field research to novel movements controlled by different motor programs. 30 men and 33 women learned novel throwing and kicking tasks, practicing with blocked, serial, or random schedules. The subjects practiced the tasks four days a week for two weeks. and then were given a postest. One week later subjects were given a retention test. Significant improvements in performance were found for all groups for both tasks; however, a significant effect for practice condition was found only for the throwing task during retention, for which the random practice schedule led to better learning than the blocked and the serial practice. These findings suggest that the blocked, serial, and random practice methods could be effectively used for tasks controlled by different motor programs but must be practiced in the same teaching session, without expecting one to be more effective in learning than any other.

This study was designed to examine the contextual interference effect on teaching golf skills in a naturalistic setting to 2 groups of 18 novice golfers who as undergraduate students practiced four foundational skills under conditions of low and high contextual interference, respectively. A t test for independent samples indicated no significant differences between groups. Findings are discussed and recommendations for research are made.

This experiment was designed to investigate varying conditions of contextual interference within two different conditions of movement tasks during acquisition on the acquisition and retention of a computerized task and transfer to a functional skill. Performance of head movements was conducted under open- or closed-task conditions and with random or blocked schedules of practice. Analysis indicated that learning under the open-task condition resulted in better retention and transfer than the closed-task condition. It is suggested that increasing the within-trial variability in the open-task condition produced a contextual interference effect. In this regard, support for Battig's predictions is provided by the current findings in that the high variability present during the open-task condition was more beneficial for retention and transfer than the low variability present during the closed-task condition. Differences between random and blocked schedules of practice on the retention and transfer data were not statistically significant.

Many studies have shown that practicing several motor tasks in a random (high contextual interference) order promotes motor learning relative to practicing the same tasks in a blocked order (low contextual interference). The facilitative effect of high contextual interference has been attributed to more frequent intertask comparisons, greater difficulty in recalling task solutions between trials, and the dissimilarity among the various tasks. Each of these explanations suggests that task difficulty is increased by high contextual interference. The hypothesis of this study was that this increase in task difficulty during practice would be associated with a higher attention load during practice. This hypothesis was supported; however, high contextual interference promoted only a transient increase in retention. The short-lived effect was attributed to the continuous nature of the task and was discussed in terms of the necessary conditions for contextual interference to emerge.

Some previous researchers assumed that the underlying process of inhibition is similar in the modally pure target-distractor task, e.g., picture-picture task, color-color task, and in the modally mixed target-distractor task, such as the picture-word task or the color-word task, but some did not. The present purpose was to compare the inhibition in the modally pure tasks (word-word task and picture-picture task) with that in the modally mixed task (picture-word task) through the effects of the two factors, that is, response set and the semantic relation between target and distractor. These factors were assumed to affect inhibition in some kinds of interference tasks. Analysis showed the effect of response set was evident on the picture-picture task but not on the word-word and the picture-word tasks. On the picture-word task, only when the distracting word was in the same set of the target picture, was the effect of the semantic relation exhibited. The differential inhibition for the three tasks was discussed.

The Stroop facilitation and interference effects as observed in the Stroop color-naming task are typically measured as the difference in naming time between the congruent or the conflicting condition and the neutral condition. The measure assumes the regression function relating the congruent or conflicting naming time to neutral naming time is linear with a slope of one and a nonzero intercept. Instead, analysis showed that the regression function subserving the facilitation effect, in fact, had a slope of less than one with a zero intercept. Analysis also showed that the regression function subserving the interference effect had a zero intercept with a greater than one slope. These results suggest that the Stroop facilitation and interference effects are the consequence of a multiplicative process by which each stage of the naming process is reduced or increased by a constant proportion. Also the appropriate measure of the Stroop effect is the ratio of the congruent (for facilitation) or the conflicting (for interference) naming time over the neutral naming time.

This investigation examined the contextual interference effect when manipulating over-all force in a golf-putting task. Undergraduate women (N= 30) were randomly assigned to a Random, Blocked-Random, or Blocked practice condition and practiced golf putting from distances of 2.43 m, 3.95 m, and 5.47 m during acquisition. Subjects in the Random condition practiced trials in a quasirandom sequence and those in the Blocked-Random condition practiced trials initially in a blocked sequence with the remainder of the trials practiced in a quasirandom sequence. In the Blocked condition subjects practiced trials in a blocked sequence. A 24-hr. transfer test consisted of 30 trials with 10 trials each from 1.67 m, 3.19 m, and 6.23 m. Transfer scores supported the Magill and Hall (1990) hypothesis that, when task variations involve learning parameters of a generalized motor program, the benefit of random practice over blocked practice would not be found.

The present study investigated reaction time with and without tapping as an interfering task. 66 undergraduate students were instructed to press and hold a button when a stimulus disappeared from a computer screen, then release it as quickly as possible when it reappeared at the end of each preparatory interval, using the preferred hand. Lengths of preparatory intervals were either 1, 2, 4, 8, 16, or 25 sec. and occurred sometimes in a regular sequence of preparatory intervals of the same length and sometimes in an irregular randomly ordered sequence. Half of the participants were assigned to tap the tabletop with the forefinger of the nonpreferred hand throughout the task. A 2 x 6 x 2 analysis of variance showed significant effects for regularity, length of preparatory interval, and the interaction between regularity and length of preparatory interval. A significant main effect for tapping indicated that reaction times were slower in the tapping group. There were no significant interactions between tapping and other variables, indicating that the pattern of reaction times did not differ significantly between the two groups. Tapping produces a dual-task interference that increases reaction time similarly across different conditions.

Different versions of the Stroop test are used; however, for most versions of the Stroop test, there are no estimations of reliability. In the present study, stimuli were presented singly on a computer screen. 55 Swiss German subjects were tested. Test-retest reliabilities of 'XXXX' strings and conflicting color words were evaluated. Response latencies and Stroop interference were quite reliable. Single-stimulus presentation made it possible also to estimate internal consistency, which was high for classical Stroop interference in this format.

The effect of irrelevant taboo and control words on performance on the Stroop task was examined. The mean response time for taboo words was higher than that for control words. Single stimulus presentation made it possible to estimate internal consistency for interference of taboo words, which was acceptable (Cronbach alpha = .80).

We describe a positive correlation between the extent of sequential counting in a random-number generation task and the magnitude of the interference effect in Stroop's color-naming task. This finding is compatible with the view that both counting and reading are highly automatized processes which constitute an inevitable source of interference in randomization and Stroop paradigms, respectively. On the other hand, cognitive psychological theories proposing that a generally biased concept of randomness would be responsible for human subjects' inability to generate true random sequences do not readily account for this correlation. Literature on repetition avoidance indicates this universal effect in random generation is likewise not explainable in terms of some 'biased concept of randomness.' Repetition avoidance ('spontaneous alternation') also occurs in lower invertebrates, is largely independent of mathematical sophistication in humans, dissipates with increasing time between consecutive responses, and is diminished by amnesia. We conclude that the failure of functionally intact organisms to display random behavior is due to basic neuropsychological limitations. In neglecting these biological foundations, 'concept of randomness' theories of randomization behavior lack explanatory value.

It has been claimed that olfactory memory is distinct from memory in other modalities. This study investigated the effectiveness of visual and verbal tasks in interfering with olfactory memory and included methodological changes from other recent studies. Subjects were allocated to one of four experimental conditions involving interference tasks [no interference task; visual task; verbal task; visual-plus-verbal task] and presented 15 target odours. Either recognition of the odours or free recall of the odour names was tested on one occasion, either within 15 minutes of presentation or one week later. Recognition and recall performance both showed effects of interference of visual and verbal tasks but there was no effect for time of testing. While the results may be accommodated within a dual coding framework, further work is indicated to resolve theoretical issues relating to task complexity.

This research examined with 48 undergraduates the effects of same and cross-modal interference in the recall of word lists. The modalities were visual and auditory for both type of presentation and type of interference. A two-way analysis of variance indicated a main effect for type of interference, with auditory interference significantly decreasing recall for both visual and auditory word lists. There was no interaction between mode of presentation and mode of interference.

66 healthy young adults, matched on age, sex, and education, were administered the Logical Memory passages of the Wechsler Memory Scale - Revised in standard order (A + B) or reverse order (B + A). Recall of both stories was similar regardless of the order of administration, suggesting that the stories were equivalent in task difficulty. Despite equivalence of story difficulty, proactive interference was not observed in this sample. These results are discussed within the context of previous research, and suggestions for further research are made.

The effects of contextual interference on learning skills of volleyball (volley, bump, serve) are influenced by the scheduling of actual practice sessions: the activities can be proposed in a repetitive practice schedule (blocked practice) by continuously repeating the same task (low interference) or in random practice schedules by performing more tasks or variations of one same activity (high interference). High contextual interference, even though causing immediate limited performance, leads to superior performance on retention and transfer tests. Four experimental groups (13 students each) were placed in conditions of random, blocked, serial, and serial with high interference practice for 8 meetings (2 tests and 6 practice). Analysis yielded significant differences among the groups on a transfer test (long transfer) for the serve, so results in this instructional setting are partially in line with those generally found in laboratory experiments.

40 and 48 subjects participated in two separate experiments aimed at reproducing the subliminal psychodynamic activation (SPA) phenomenon and taking into account the major methodological critique by Fudin (1986, 1990). Subjects were first exposed either to a full or one of all possible partial symbiotic messages and then to their anagram equivalents. Confounding and irrelevant influences were controlled; the results indicate that only the full symbiotic message improved motor performance. This strongly suggests that subjects encode the meaning of the full message and supports an interpretation in terms of an alleviation of an internal symbiotic conflict leading to a state of calmness conducive to improved motor performance.

Three experiments were performed to study the effects of an ongoing task on the annoyance response to noise. In the first two experiments a total of five tasks were used: three versions of a proofreading task, a finger-dexterity task, and a complex reaction time (RT) task. Subjects performed the tasks during exposure to two levels of a continuous broadband noise. Task was of no consequence for rated annoyance. Four tasks were used in Experiment 3: proofreading, complex RT, grammatical reasoning, and simple RT. A third type of noise, irrelevant speech, was added to the broadband noises. Rated annoyance was lower during simple RT than during the reasoning and proofreading tasks, especially in the irrelevant speech condition. The difference corresponded to a 6-dB difference in noise level. It was concluded that task differences probably only explain a small part of the widely differing noise tolerance levels at different work places.

Previous studies of contextual interference have shown that practicing several motor skills randomly (high contextual interference) facilitates retention and transfer in comparison to practicing the same tasks in a blocked order (low contextual interference). However, many studies have not supported this phenomenon in motor learning, and some researchers have questioned whether the effect can be tested by using only a few trials on the transfer test. The present study used a different methodological approach in which the number of test trials was increased to assess whether the contextual interference effect is sustained over an extended number of trials in the transfer phase. Undergraduate students (N = 32) were randomly allocated to either a blocked or random group. The participants practiced 80 acquisition trials in the dart-throwing task from distances of 300 cm and 420 cm, using two different grips. The transfer test after a 10-min. interval consisted of 40 trials with a new grip at a distance of 360 cm. The results did not support the contextual interference effect since there were no significant differences between groups on transfer. These findings suggest that the contextual interference effect may not be a global learning phenomenon which can be generalized to all learning situations.

In the present study, interactions of contextual interference and the cognitive style reflection-impulsivity were examined for training and retention performance. 64 subjects were randomly assigned to either a random or blocked practice schedule in learning a cursor-movement task. Reflectivity indices were determined by means of our computerized version of the Matching Familiar Figures Test. Analysis showed that the generally positive effect of practicing under a random practice schedule decreased for more reflective subjects. Further, training under a random practice schedule forced impulsive subjects to behave more like reflective ones, which improved their performance at retention. It was concluded that reflection-impulsivity is an important factor to be incorporated into the design of effective training programs.

Proactive interference in motor skill acquisition occurs when a desired response in adversely affected by a previously learned skill. The purpose of this study was to assess the effects of learning a forehand tennis grounedstroke on the subsequent learning of a backhand. 96 subjects equally representing seventh and eighth grade boys and girls who had never played tennis were randomly assigned to two methods of instruction. This resulted in four groups of 24. The experimental groups received instruction and practice in a forehand skill. The experimental and control groups received backhand instruction and practice and both groups were tested on backhand. Results of a 2 X 2 multivariate analysis of variance indicated significant between-subjects main effects for sex and groups. There were significant within-subjects effects for days and group x days. These results suggest that learning the forehand independent of the backhand may interfere with learning the backhand.

For three consecutive days, two groups of adult female cockroaches (Periplaneta americana) (ns = 10) received inescapable shock. 24 hr. later one group was exposed to 10 min. of forced exercise on a treadmill while the other group received no exercise. Both groups were then run in a shuttlebox escape task. The cockroaches exposed to forced exercise did not become helpless in the shuttlebox escape task.

40 subjects given equal and random amounts of practice on a variable speed pursuit rotor exhibited no contextual interference effect on the performance of two transfer tasks (35 and 60 rpm) 48 hours later.