Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo‐random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo-random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Time perception with and without a concurrent nontemporal task

Prospective time estimates were obtained from human subjects for stimulus durations ranging from 2 to 23 sec. Presence and absence of a concurrent nontemporal task was manipulated within subjects in three experiments. In addition, location of the task within temporal reproduction trials and psychophysical method were varied between groups in Experiments 2 and 3, respectively. For long-duration stimuli, the results of all three experiments conformed to results in the literature, showing a decrease in perceived duration under concurrent task conditions, in accord with attentional resource allocation models of timing. The effects of task location and psychophysical method on time estimates were also compatible with this analysis. However, psychophysical functions obtained under task conditions were fit well by power functions, an outcome that would not be anticipated on the basis of attention theory. The slopes of the functions under no-task conditions were steeper than those under task conditions. The data support the perceptual hypothesis that different sources of sensory input mediate timing under task and no-task conditions.     

Remembered duration: working memory and the reproduction of intervals

On the basis of attention allocation models of time estimation, the role of working memory in prospective duration reproduction is explored. In four experiments, adult participants performed a counting task (duration, 400 sec) that allowed coordinative and sequential demands on working memory to be varied. After completing the counting task, the participants reproduced the time that they had worked on this task It emerged that (1) increased coordinative demands on working memory (but not increased sequential demands) reduced the accuracy of prospective duration reproduction (Experiments 1 and 2), (2) presenting context information during the reproduction phase enhanced the accuracy of the reproduced duration (Experiment 3), and (3) individual differences in coordinative working memory capacity affected duration reproduction in the same direction as the experimental manipulation of coordinative task demands (Experiment 4). The results suggest that attention allocation models of time estimation may benefit from taking a more differentiated view of the types of attentional demands that affect temporal cognition.     

The perceived informational value and affective consequences of choice behavior and intermediate difficulty task selection

Four experiments were conducted that examine the affective and informational determinants of risk-preference behavior. In the initial two experiments, subjects classified according to their level of achievement needs expressed a preference among tasks varying in difficulty. In two of the experimental conditions, instructions, respectively, conveyed that performance at the task chosen should either maximize satisfaction or the information gained about one's ability and effort expenditure. It was found that the majority of all subjects preferred to undertake tasks of intermediate difficulty and that both positive affect and information gain were perceived to be optimal at or near the level of intermediate difficulty. Experiments III and IV investigated at what level of task difficulty individuals most desire information about their performance. Police trainees and high school students with disparate self-concepts of respective target shooting and high-jumping ability were able to receive limited but self-selected performance feedback at a series of achievement tasks that varied in difficulty. The data revealed that the tasks selected for feedback became objectively less difficult as the self-perception of ability decreased. In addition, the tasks chosen for feedback were near the intermediate subjective certainty of success level for all subjects. It was contended that the data contradict Atkinson's model of choice but support an attributional conception. The general issue of affective versus informational models of motivation was discussed.     

Spatial complexity and hand usage on the Block Design Test

The Block Design test is a task utilizing spatial ability, on which subjects are required to arrange red and white blocks in a pattern similar to one presented on a stimulus card. 69 right-handed subjects were presented a series of trials which varied in difficulty or spatial complexity. The amount of time that each subject's hand was in contact with the blocks during each of the reproduction attempts was recorded. Analysis of these times shows that subjects use their right hands with greater frequency only on tasks of low and moderate spatial complexity. This preference is not present on tasks of high spatial complexity. Interpretations of this finding are offered.     

Prospective Memory and Divided Attention

In three experiments, we manipulated the processing demands of a concurrent task to test the hypothesis that an event-based prospective memory task satisfies a criterion of automaticity proposed by Hasher and Zacks (1979). As in the previous studies, a prospective memory task (pressing a key whenever a target word was presented) was embedded within a short-term memory task (remembering seven words). In addition, participants performed a concurrent memory task which varied in difficulty. Participants repeated either 0 to 6 randomly generated digits or a single word. In all three experiments, short-term memory performance was influenced by the concurrent memory load. Prospective performance, in contrast, was not affected by the memory load even though an attempt was made to increase the difficulty of the prospective task by manipulating the specificity of the target instructions (Experiment 2) and the number of target words (Experiments 2 and 3). The results are discussed within the framework of automatic processing.     

Information processing and estimation of short time intervals.

Duration estimates were assessed by the method of reproduction with filled reproduction intervals. Mental arithmetic, reading and mirror-image drawing were used in pairs as initial and/or reproduction tasks. All nine possible pairs of tasks were used in a 9 X 5 X 5 mixed design with five Ss per task pair and five interruption intervals for each initial task. Results indicated that, when arithmetic was used as the initial task, Ss underestimated the duration of the initial interval. When arithmetic was used as the reproduction task, Ss overestimated the duration of the initial interval. A significant correlation was obtained between arithmetic outputs and the lengths of the duration estimates. Results are interpreted as supportive of Burnside's (1971) interpretation of Ornstein's (1969) storage-size hypothesis.     

Aging and shifts of visual spatial attention.

Three experiments examined adult age differences in the efficiency of endogenous (voluntary) and exogenous (involuntary) attention shifts. Younger and older subjects performed a spatial cuing task in which abruptly onset peripheral cues (Experiment 1) or central, symbolic cues (Experiments 2 and 3) were presented before a target stimulus at intervals ranging from 50 to 250 ms. With peripheral cues, the magnitude of cuing effects was at least as great for older as for younger adults and followed a similar time course. Similar results were obtained with symbolic cues, although cuing effects for older adults varied with cue difficulty. The results suggest that cue encoding may decline with advancing age but that the efficiency of the shift process is preserved.     

Immediate and remote time estimation — A comparison

The influence of the length of time elapsing between the termination of an interval on its estimated duration was tested in three experiments. In the first experiment, 89 subjects performed the W, C, and CW tasks of the Stroop color-word test. The duration of each of these three tasks, which was 10 second in reality, was estimated twice by every subject. Once, immediately upon completion of the task (IE), and a second time 90 seconds later (RE), both under prospective paradigm. The nature of the relationship between task difficulty and its estimated duration was found to be different in IE and RE. A negative relationship was found in IE while in RE no significant difference was found between difficulty levels. In the second experiment it was found that RE's trend was not caused by estimation order. In the third experiment IE and RE were tested under prospective and retrospective paradigms. In the perspective paradigm the results obtained in experiment 2 were replicated. In the retrospective paradigm the relationship between task difficulty and time estimation was, unlike the prospective paradigm, negative in both IE and RE. The significance of the results to time estimation theory was discussed.     

Effects of attention and external stimuli on duration estimation under aprospective paradigm

The study examined whether there are two independent cognitive factors affecting duration estimation. In two experiments, we manipulated simultaneously and independently two variables, namely, the level of attention to the lapse of time and the quantity of perceived changes, and examined their effects on duration estimation under a prospective paradigm. The duration was estimated to be longer when subjects attended to the lapse of time than when they attended to tasks during the target interval (Experiments 1 and 2). The characteristics of external stimuli irrelevant to the tasks, namely, the rate of presentation of sounds (Experiment 1) and the velocity of moving dots (Experiment 2), affected duration estimation, even though the attention level was little changed by these stimuli. These findings suggest that there are at least two independent cognitive factors that affect duration estimation.     

Effects of two tasks and two levels of difficulty upon surface electrogastrograms

The effects of differentiation, novelty, and difficulty of ability tasks upon electrogastrographic activity of healthy subjects during digestion were investigated. Electrical recording of activity of the stomach by means of surface electrodes was performed in 40 healthy volunteers before and after easy or hard tasks. 20 subjects had to complete puzzles; the others had mental arithmetic. Both groups were matched in terms of scores on easy and difficult tasks. Baseline recordings were performed before each trial. The number of waves with peak amplitude greater than 100 mu v on electrogastrographic recording during each time span was measured, using a visual analysis. There was a significant decrease in number of waves/min, during task performance. A more pronounced decrease was produced by subjects working on puzzles than those working on mental calculation and by subjects working on easy tasks than those working on difficult tasks when the easy preceded the difficult ones. A larger decrease was obtained when the tasks of comparable difficulty were performed first. Emotional correlates such as anger and irritability were suggested to play a role in the interpretation of results.     

Selective disruption of hypermnesia for pictures and words

In this study, we investigated the effects of various interpolated tasks on hypermnesia (improved recall across repeated tests) for pictures and words. In five experiments, subjects studied either pictures or words and then completed two free-recall tests, with varying activities interpolated between the tests. The tasks performed between tests were varied to test several hypotheses concerning the possible factor(s) responsible for disruption of the hypermnesic effect. In each experiment, hypermnesia was obtained in a control condition in which there was no interpolated task between tests. The remaining conditions showed that the effect of the interpolated tasks was related to the overlap of the cognitive processes involved in encoding the target items and performing the interpolated tasks. When pictures were used as the target items, no hypermnesia was obtained when subjects engaged in imaginal processing interpolated tasks, even when these tasks involved materials that were very distinct from the target items. When words were used as the target items, no hypermnesia was obtained when the interpolated tasks required verbal/linguistic processing, even when the items used in these tasks were auditorily presented. The results are discussed in terms of a strength-based model of associative memory.     

Control of fixation duration in a simple search task

To obtain insight into the control of fixation duration during visual search, we had 4 subjects perform simple search tasks in which we systematically varied the discriminability of the target. The experiment was carried out under two conditions. Under the first condition (blocked), the discriminability of the target was kept constant during a session. Under the second condition (mixed), the discriminability of the target varied per trial. Under the blocked condition, fixation duration increased with decreasing discriminability. For 2 subjects, we found much shorter fixation durations in difficult trials with the mixed condition than in difficult trials with the blocked condition. Overall, the subjects fixated the target, continued to search, and then went back to the target in 5%–55% of the correct trials. In these trials, the result of the analysis of the foveal target was not used for preparing the next saccade. The results support a preprogramming model of the control of fixation duration. In a simple search task, control of fixation duration appears to be indirect.     

青老年组不同难度下心算活动的脑功能磁共振成像研究

应用功能磁共振成像技术研究不同心算难度下脑区的活动以及年龄的影响。14名志愿者（20～29岁青年和60～69岁老年被试各7名）参加了该实验。实验任务为2个难度水平的连续减法心算,分别为1000—3和1000—17。结果表明：（1）心算加工激活了额叶和顶叶的许多脑区;（2）大脑左半球是心算加工的优势半球,但随着心算难度加大,大脑一侧化程度下降,而年老加剧了这一趋势;（3）青年组进行简单心算（1000—3）时,额中回未见明显激活,而老年组进行简单心算时,该脑区被明显激活。总体上,额叶和顶叶在心算活动中起着重要作用,而任务难度和年龄对心算加工时脑活动的影响以额中回区最为明显。     

Amount and duration of attentional demands during visual search

Previous research has suggested that, in visual-search tasks, the comparison between target and display items does not require attentional capacity. In the present experiment we used a secondary-task paradigm to distinguish the amount and duration of the attentional demands of visual search. The subjects performed visual search (the primary task) and tone detection (the secondary task) concurrently over the course of five experimental sessions (1,440 trials). For each subject, target-response mapping was either consistent or varied for Days 1-5. The results indicate that the amount of attentional demand, as reflected in secondary-task performance, increased as a function of display size in the search task. Switching from consistent to varied mapping in a sixth experimental session increased both the amount and the duration of the attentional demands of the search. The present results support models of visual-search performance in which the comparison of target and display items requires attentional capacity.     

Temporal order in memory and interval timing: an interference analysis

The effect of varying load in memory tasks performed during a time interval production was examined. In a first experiment, increasing load in memory search for temporal order affected concurrent time production more strongly than varying load in a spatial memory task of equivalent difficulty. This result suggests that timing uses some specific resources also required in processing temporal order in memory, resources that would not be used in the spatial memory task. A second experiment showed that the interference between time production and memory search involving temporal order was stronger when, during the timing task, a decision was made on the temporal position of a memory item, than when information on temporal order was retained throughout the interval to be produced. These results underscore the importance of considering the specific resources and processes involved when the interference between timing and concurrent non-temporal tasks is analyzed.     

Effects of attention manipulation on judgments of duration and of intensity in the visual modality

The “attentional model” of time estimation assumes that temporal judgments depend on the amount of attention allocated to the temporal processor (the timer). One of the main predictions of this model is that an interval will be judged shorter when attention is not allocated to the temporal parameters of the task. Previous studies combining temporal and nontemporal tasks (dual-task method) have suggested that the time spent processing the target duration might be a key factor: The less time devoted by the subject to the temporal task, the shorter the judged duration. In the two experiments presented here, subjects were asked to judge both the duration of a visual stimulus and an increment in intensity occurring at any time during this stimulus. In the second experiment, trials without intensity increments were added. The main result is that the judged duration was shorter when the increment occurred later in the stimulus or did not occur. In those cases, subjects had been expecting increment occurrence during most part of the stimulus and thus had focused for a shorter time on stimulus duration. We propose that attention shifts related to expectancy and to detection of the increment reduce subjective duration.     

Effects of prime task on affective priming by facial expressions of emotion

Priming of affective word evaluation by pictures of faces showing positive and negative emotional expressions was investigated in two experiments that used a double task procedure where participants were asked to respond to the prime or to the target on different trials. The experiments varied between-subjects the prime task assignment and the prime-target interval (SOA, stimulus onset asynchrony). Significant congruency effects (that is, faster word evaluation when prime and target had the same valence than when they were of opposite valence) were observed in both experiments. When the prime task oriented the subjects to an affectively irrelevant property of the faces (their gender), priming was observed at SOA 300 ms but not at SOA 1000 ms (Experiment 1). However, when the prime task assignment explicitly oriented the subjects to the valence of the face, priming was observed at both SOA durations (Experiment 2). These results show, first, that affective priming by pictures of facial emotion can be obtained even when the subject has an explicit goal to process a non-affective property of the prime. Second, sensitivity of the priming effect to SOA duration seems to depend on whether it is mediated by intentional or unintentional activation of the valence of the face prime.     

Age-related changes in duration reproduction: involvement of working memory processes

The aim of the present research was to study age-related changes in duration reproduction by differentiating the working memory processes underlying this time estimation task. We compared performances of young and elderly adults in a duration reproduction task performed in simple and concurrent task conditions. Participants were also administered working memory tests to measure storage and central executive functions. Findings indicated a differential involvement of working memory storage and central executive functions in age-related differences in temporal tasks. The limited storage capacities explained age-related changes in the simple task of duration reproduction, and the dysfunctioning of central executive functions accounted for age-related changes in duration reproduction performed in a concurrent task condition, which involves greater attentional resources.