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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.

This article describes examination of short-term memory. Experiment design, possible causes for a low forgetting rate, and similarity with earlier results are discussed.

Two experiments were conducted to examine the basis of Stroop interference using a color-word matching task. The objective was to determine whether interference can be eliminated and reestablished later by manipulating the involvement of the semantics system in the visual decision task. Results based on the meaning decision task and the visual decision task indicate that semantic competition is the major source of Stroop and Stroop-like interference.

Thirty undergraduates participated in an experiment investigating the effect of the arithmetic difference between stimulus identity and stimulus numerosity in a numerical version of the Stroop task. It was found that digits symbolically close to the enumeration response reliably produced larger interference than digits that were farther from the enumeration response. This semantic distance effect was found with different numerosities (1-9) and different enumeration processes (counting and subitizing), and it increased as a function of numerosity in the subitizing range. These findings suggest that digit identity autonomously activates a magnitude representation organized as a compressed number line.

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 role of reason generation in dogmatic thinking was examined by means of cognitive response analysis. In Experiment 1, dogmatism was associated with greater confidence in judgments as a result of postjudgment generation of more supporting and less contradictory evidence. Experiment 2 produced similar results for confidence judgments with prejudgment reason generation, except that no difference in supporting evidence was found as a function of dogmatism. Experiment 3 showed that dogmatism was associated with greater output interference in reason generation, leading to greater primacy effects in likelihood judgments. A delay between generation of masons reduced output interference effects, but only for those low in dogmatism who showed a recency effect. The results were interpreted in terms of cognitive mechanisms in dogmatic thinking after artifactual and motivation explanations had been ruled out.

Two experiments used a 2-list interference paradigm to investigate attributes of an interfering list that were predicted to reduce the retroactive interference to recalling an earlier learned list. In Experiments 1a and 1b, word frequency was manipulated such that the first list was always of low frequency (Experiment 1a) or was always of high frequency (Experiment 1b), and the second list was systematically varied as of either high or low frequency. Contrary to a list discrimination account, high-frequency words always interfered less. In Experiment 2, an organized interfering list was shown to reduce significantly retroactive interference. List cohesion, ease of learning, interitem associations, and the similarity of the results to Bower and Mann's (1992) postlearning cue (i.e., the postinformation effect) are discussed., For almost 70 years, interference has been acknowledged as one of the most pernicious causes of human forgetting (McGeoch & McDonald, 1931). The foundation of interference theory came from the [...]

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 relative speed of processing-automaticity (RSOP-A) and contextual disintegration models were utilized to examine the age-related increase in Stroop effect or Stroop interference effect in older adults. It was hypothesized that Stroop effect indicated the increase in response latency related to color word and incongruent color word naming. Results of the experiments showed that response dominance was higher in older than younger adults which led to increased reliability in color-naming latency. Also, the prefrontal cortex played a role in Stroop interference.

Two experiments were conducted using electrophysiological recordings in an attempt to explain the reason for the response time delay in the specific index of perception and categorization, also known as the P3 wave. It was believed that the locus of interference occurred when a person attempted to achieve two tasks at the same time. Results revealed the occurrence of the dual-task interference in the psychological refractory period paradigm after the early sensory stage and prior to the motor execution stage. Also, interference occurred at the stage of processing.

In 4 experiments the authors used 2-stage designs to study susceptibility to interference in human discrimination learning. The experiments used a food allergy task. In Experiment 1, participants were presented with a discrimination in Stage 1 in which Food A predicted an allergy outcome (A [right arrow] O). In Stage 2, when combined with Food B, Food A predicted the absence of the allergy (B [right arrow] O, AB [right arrow] no O). In the test phase, Food A was found to have retained its Stage 1 association with the allergy despite the potentially interfering Stage 2 trials. In Experiment 2, a discrimination between 2 compounds (AB [right arrow] O, CD [right arrow] no O) remained intact despite subsequent complete revaluation of the elements, (A [right arrow] no O, B [right arrow] no O, C [right arrow] O, D [right arrow] O); in Experiments 3 and 4, a discrimination between 2 pairs of elements (A [right arrow] O, B [right arrow] O, C [right arrow] no O, D [right arrow] no O) remained intact despite subsequent complete revaluation of the AB and CD compounds, (AB [right arrow] no O, CD [right arrow] O). These experiments yielded evidence of remarkable resistance to interference in human discrimination learning. The results are at variance with the predictions of J. M. Pearce's (1987, 1994a) configural theory of associative learning.

How are second-order (texture-defined) and third-order (pattern-tracking) motions processed in our brains? As shown here in the context of an ambiguous motion task involving a nominal second-order stimuli first devised by Werkhoven et al., [Werkhoven, P., Sperling, G. & Chubb, C. (1993) Vision Res. 33, 463-485.], the observers fell into two distinct groups based on the direction of perceived motion. The differences were interpreted in terms of the algorithms used to extract motion: one group by using a second-order motion process and the other by using a third-order motion process. This was investigated further using a dual-task paradigm in which the interference between two tasks indicated the nature of processing involved. Observers who used third-order motion processing experienced interference with letter recognition and a more severe interference in dual third-order motion tasks. Observers who used second-order motion processing experienced interference with another second-order motion detection but not with letter recognition. Insofar as task interference implies the need for attention, the complex interference effects and the apparently paradoxical interference effects of second-order motion perception imply that there are multiple forms of attention. Whether two tasks interfere depends on whether they require the same form of attention. Insofar as spatio-temporal processing is assumed to be carried out in the dorsal stream and pattern recognition in the ventral stream, the interference patterns suggest that second-order motion may be computed entirely in the dorsal stream, and third-order motion may involve two computational processes, one of which shares computational resources with the letter recognition task in the ventral stream.

The J. D. Cohen, K. Dunbar, and J. L. McClelland (1990) model of Stroop task performance is used to model data from a study by D. H. Spieler, D. A. Balota, and M. E. Faust (1996). The results indicate that the model fails to capture overall differences between word reading and color naming latencies when set size is increased beyond 2 response alternatives. Further empirical evidence is presented that suggests that the influence of increasing response set size in Stroop task performance is to increase the difference between overall color naming and word reading, which is in direct opposition to the decrease produced by the Cohen et al. architecture. Although the Cohen et al. model provides a useful description of meaning-level interference effects, the qualitative differences between word reading and color naming preclude a model that uses identical architectures for each process, such as that of Cohen et al., to fully capture performance in the Stroop task.

In this reply, the authors point out that the simulations reported by S. M. Kanne, D. A. Balota, D. H. Spieler, and M. E. Faust (1998) did not incorporate mechanisms proposed to explain set size effects in J. D. Cohen, K. Dunbar, and J. L. McClelland (1990). The authors report a new simulation that incorporates these mechanisms and more accurately simulates S. M. Kanne et al.'s empirical data. The authors then point to other factors that could be explored in a more complete test of their model. The use of feed-forward rather than recurrent inhibition is discussed as a potentially important limitation of their original model, and recent work addressing this issue is described. The authors also discuss possible differences between word reading and color naming in the Stroop, task. Although such differences may exist, the authors retain their earlier view that such differences do not reflect a dichotomy between automatic and controlled processing.

Observers watched for 1 or 2 colored words as targets presented in lists of distractor strings (10 items/s). Identification of 1 target (T1) temporarily reduced the accuracy of reporting a 2nd target (T2). This attentional blink (AB) effect was most pronounced when T1 and T2 occurred close together in time. Use of recognition tests (instead of recall) improved performance but did not eliminate the AB effect. The AB effect was found with both word and nonword distractors, a smaller AB effect was found with consonant string distractors, and the AB effect was substantially attenuated with strings of unfamiliar characters (a false font). Analyses of errors indicated that the 2nd target is frequently replaced or corrupted by the following distractor during the blink. The AB effect appears to result from both attentional and mnemonic processes.

Five experiments showed that interference resulting from verbalizing visual stimuli (verbal overshadowing) can be reduced by reintroducing visual cues present at encoding. Object color and background color were used as cues. Participants learned either easy- or hard-to-name figures and then performed an image rotation task. Before performing the imagery task, participants were re-presented with the color patch associated with each figure. Color re-presentation attenuated the impairment associated with easy-to-name stimuli (Experiment 1) as well as labeled hard-to-name stimuli (Experiment 2). However, background color cues had no effect on imagery performance (Experiment 3). Experiment 4 showed that naming the object colors at encoding makes color retrieval cues ineffective. Finally, Experiment 5 showed that object color cues can help participants to overcome previously exhibited impairment resulting from covert verbalization.

The manner by which developing children resist interference effects from irrelevant information is examined. Of particular significance are the influence of perceived structure and selective attention on interference. Stimulus response translation is emphasized over perceptual filtering and motor preparation processes in decreasing interference effects in developing children.

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.

Previous evidence suggests that a disruptive stimulus presented during the delay interval of a delayed matching-to-sample trial increases the rate of forgetting by pigeons. However, disruptive events have generally been presented for a period of time proportional to the delay interval. Thus, the observed increase in forgetting may be the result of greater exposure to these events at longer delays than at shorter ones. This possibility was examined by comparing the effects of houselight illumination for the entire delay, half the delay, or a constant 1.5 sec of each delay on pigeons' delayed matching-to-sample accuracy. Presenting the houselight for a period of time proportional to each delay (i.e., the entire delay or half the delay) impaired accuracy more at longer delays than at shorter delays. By contrast, when the houselight was illuminated for 1.5 sec, irrespective of delay length, there was a greater impairment in accuracy at shorter delays than at longer delays. Thus, the increased rate of forgetting previously reported in the literature may be the result of unequal application of a disrupting stimulus across delays.

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.

Do number-fact retrieval (4 [multiplied by] 6 = ?) and numeral reading (e.g., transcoding 46 into 'forty six') access the same retrieval structures? Data from the present experiment suggest that they do. Under instructions to respond quickly, adults performed simple multiplication problems oriented horizontally or vertically with operands presented simultaneously or with a 500 ms preview of one operand. Errors involving congruent operand intrusions (e.g., 2 [multiplied by] 8 = 24 or 9 [multiplied by] 6 = 36) were most frequent when conditions afforded the left-to-right encoding sequence that is standard for reading multi-digit numbers. Ninety percent of such intrusions involved the correct answer to another simple multiplication problem (e.g., 4 [multiplied by] 8 = 28) rather than a miscellaneous answer (e.g., 4 [multiplied by] 8 = 38). This high rate of arithmetically related intrusions suggests that numeral reading and verbal production of number facts involve a shared representational system.

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.

Whether attention to a local part of a visual display can prevent access to semantic information in form matching tasks with objects was studied. A first picture containing a line segment (the reference) was followed by 2 lateral objects also containing a line segment (a target and a distractor). Participants matched the line segments according to either their orientation or color. Effects of semantic information were assessed by manipulating the semantic relations among the pictures surrounding the reference, target, and distractor. Semantic information affected performance in the orientation matching task, but not in the color matching task. Results suggest the existence of separate selection mechanisms in vision. Selection of local colors for response purposes can be based on inhibition of the form pathway (eliminating semantic effects on matching). Selection within the form pathway can involve a bias toward global shape (the picture). Once attention is allocated to global shape, associated semantic representations are activated and semantic effects on matching emerge.

We provide evidence that information that organizes interfering text after learning improves recall of original text to which the organizing information does not pertain. Subjects learned two text passages. The second passage was difficult to understand without the aid of a picture that provided the necessary clarifying context. Using the picture as an organizing cue for the second passage (just before retrieval of the first passage) improved recall of the first passage. We address and rule out an alternate explanation that is based on the difficulty of the task immediately preceding recall. These results contradict several traditional hypotheses about interference, and they are difficult to explain with several current models of memory. Implications for learning are discussed., Memory research has shown that people experience interference when learning two sets of material. In retroactive interference, for instance, the second set of material interferes with the first set, resulting [...]

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.

Using multiplication facts, this experiment demonstrated an interference effect in the number-matching task. Here, subjects verified the presence of a target number (e.g., 8) in a previously presented cue (e.g., 5 x 8) that was masked after 60 ms. The SOAs between cue and target were 100, 120, 220, and 350 ms. Subjects were slower to reject targets that were the product of the cue (e.g., 40) than to reject unrelated targets (e.g., 42), but this was true only at the 100- and 120-ms SOAs (i.e., the interference effect). This pattern is consistent with the interference effect found by LeFevre and colleagues using addition facts. Furthermore, the present result supports the interpretation that the interference effect previously found with addition facts was due to obligatory activation and not to automatic counting.

This experiment examines the interference between tapping and searching in short-term memory (STM). In a concurrent processing condition, the subject first memorized a set of digits, and then executed a series of 17 taps separated by 2 s subjective time intervals. In each intertap interval, a probe was presented for comparison with the items in the memory set. The amount of processing in STM was varied from series to series by manipulating the number of items in the memory set. The results showed that mean duration and variability of intertap intervals increased proportionally with memory set size. This effect is explained by interference between processing in STM and the timing component of the tapping performance. Tapping sensitivity to memory load suggests that, under some conditions, variations in tapping performance are valid indicators of STM processing requirements of a concurrent primary task.

Timing of postevent information has different qualitative effects on six-month-old infants' memory. With short exposure delays, the postevent information interferes with recognition of the original event (memory impairment), and is treated as a part of the original event (memory facilitation). Both original and interpolated information get reactivated if the postevent exposure is in the early retention interval. Exposing postevent information after longer delays evokes response to a novel event (categorization).

In a 2-list interference paradigm, G. H. Bower and T. Mann (1992) found reduced retroactive interference when they informed people who had just learned List 2 that all of the List 2 items shared a feature that was not shared with List 1 items. Although the reliability of this postinformation effect has been challenged (e.g., G. H. Bower, A.D. Wagner, S. E. Newman, J. D. Randle, & M. J. Hodges, 1996), the authors of the present study obtained the effect in 3 experiments and also showed that the speed of recall was enhanced by providing such a postinformation cue to learners. Boundary conditions for the occurrence of the postinformation effect are discussed, as well as the role of source monitoring in producing it.

Interfering with stimulus identification can enhance later explicit memory performance. This counterintuitive (and theoretically unexpected) phenomenon was investigated in 5 experiments. Perceptual interference enhanced category-cued recall (a conceptually driven explicit test) but had no effect on a comparable implicit memory test, category-exemplar production. This dissociation was obtained across higher levels of priming and with high-frequency as well as low-frequency exemplars. Furthermore, although perceptual interference enhanced old-new recognition memory, it did not enhance rhyme recognition (a data-driven explicit test) or source discriminability. Explanations based on enhanced semantic elaboration or enhanced encoding of spatio-temporal context do not account for the perceptual-interference effect. An account based on compensatory processing of higher level perceptual representations remains viable and is discussed in terms of the transfer-appropriate processing framework and the item-specific-relational distinction.

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.

The visual identification of objects is a sustained rather than a high-speed process, one in which representations of the objects affect subsequent behavior. A previously identified object interferes with the identification of other objects for almost half a second or more. This is much more than that predicted by the high-speed model for visual attention. The number of objects identified determines the duration of interference. Even nontargets interfere with subsequent identification. The interference is probably due to a competition among the objects for the limited visual processing resources.

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).

Memory for A-B word pairs (e.g., child-apple) was tested by a cued recall test (e.g., child-app_). Showing an A-C 'relative' (e.g., child-bicycle) reduced recall, especially if it was shown recently and was highly accessible (Experiments i and 2). In Experiment 3, a relative facilitated recall if it was semantically similar to the target (A-B[prime]: child-cookies) but interfered if it was semantically dissimilar (A-C: child-fever). The best explanation for these results is that the relative primed features that affected the functional retrieval cue, and that interference occurred if the cue did not match the trace for the target (Martin, 1972). In other words, the interference effects are an example of cue-dependent forgetting. Neither blocking nor a discrimination process can account for these findings, although some evidence for a discrimination process has been found with other materials.

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.

Classical interference effects were examined in preschool and kindergarten children's paired-associate recall (Experiment 1) and free recall (Experiment 2). Children in the control conditions learned a single picture list, whereas children in the experimental conditions learned 2 picture lists in succession. After 24 hr, children recalled items from the one list they had learned (control conditions), items from only List 1 (retroactive interference conditions), or items from both lists (modified free-recall conditions). Analyses based on the trace-integrity framework indicated that (a) children were susceptible to interference, (b) the locus of interference effects was at storage, (c) both younger (preschool) and older (kindergarten) children experienced similar amounts of interference, and (d) variations in trace strength generally did not modulate the magnitude of interference effects.

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.

It can be argued that imaginary practice and physical practice are functionally similar. Evidence in support of this hypothesis comes from several experiments demonstrating that interference effects from imaginary practice in motor learning and motor memory are similar in both direction and size to those resulting from physical practice. The purpose of the present study was to provide additional support for this finding using a retroactive interference paradigm. Sixty participants were required to practise performing a simple motor task that was to be completed in a criterion time of 700 ms. They then were randomly assigned to one of six groups. These groups differed in the amount and type of interpolated practice they experienced. One physical practice group attended one session of interpolated activity involving physical practice of another motor task. The other physical practice group participated in two such sessions. One imagery group attended a single session entailing imaginary practice of the same interpolated motor task, while the other imagery group had two such sessions. A fifth group experienced a combination of physical practice and rest periods for two interpolated sessions. A control group did not experience any interpolated activity sessions. Following the interpolated activity sessions, all groups were given a retention/reacquisition test on the original motor task. Imaginary and physical practice during the interpolated activity sessions caused similar interference effects on retention/reacquisition. All groups showed greater deviation from the criterion movement time (700 ms) during the retention test than the control group, and these deviations were in the expected direction given the nature of the interpolated motor task., How functionally similar are imaginary practice and physical practice? An examination of the mental imaginary (practice) literature reveals studies in which imaginary and physical practice have produced virtually identical positive [...]