Effects of time of day and information importance on adults' memory for a short story

An experiment is reported that tested subjects' memory for information in a short story, either immediately after hearing the story or after a delay of one week. The story was presented, and the subjects tested, either in the morning or in the afternoon. The results showed that, although there was no overall effect of time of day of presentation on recall, relatively more important information from the story was recalled after a delay following presentation in the late afternoon, and more unimportant information following original presentation in the morning. The time of day of the delayed recall test did not have any effect on performance.     

OPTIMAL TIME OF DAY AND THE MAGNITUDE OF AGE DIFFERENCES IN MEMORY

Abstract— Across two studies comparing younger and older adults, age differences in optimal performance periods were identified (Study 1), and then shown to be an important determinant of memory differences (Study 2). A norming study showed that while most younger adults were Evening or Neutral types, as determined by a standard questionnaire, the vast majority of older adults were Morning types. A second study compared the recognition performance of younger and older adults tested in the morning or in the late afternoon. Substantial age differences were found in the late afternoon, when younger but not older adults were at their optimal times. However, no age differences in memory performance were found in the morning, when older but not younger adults were at their peak period. Thus, synchrony between optimal performance periods and the time at which testing is conducted may well be a critical variable in determining group differences in intellectual performance, particularly between older and younger adults.     

Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers

Forty habitual, heavy coffee drinkers (M = 5.7 cups/day) participated in two experimental sessions. Participants were deprived of their morning coffee for one of the laboratory sessions, not deprived the other. During each session, subjects consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. This study found that caffeine continues to cause blood pressure increases with chronic, heavy consumption and that these effects do not appear to habituate with regular use. Subjects reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress.     

BEHAVIORAL TREATMENT OF CAFFEINISM: REDUCING EXCESSIVE COFFEE DRINKING

Excessive coffee drinking can have deleterious effects because of the large amounts of caffeine that are ingested. Caffeine is thought to be addicting, and prolonged and excessive use can lead to caffeinism, a condition that has serious behavioral and physiological side effects. The present study developed and evaluated a treatment program to reduce excessive daily coffee drinking to moderate and presumably safer levels. Three habitual coffee drinkers received individualized changing criterion programs that systematically and gradually reduced their daily caffeine intake. The coffee drinkers were required to self-monitor and plot their daily intake of caffeine. They received monetary prizes for not exceeding the treatment phase criteria and forfeited a portion of their pretreatment deposit when they did. Their coffee drinking decreased from almost nine cups per day (over 1100 mg of caffeine) during baseline to less than three cups per day (less than 343 mg) at the end of treatment or a reduction of 69%. The treatment effect was maintained during a 10-month follow-up, averaging a 67% reduction from baseline. The program appears to be a reasonable method of reducing and then maintaining daily caffeine intake at less harmful levels.     

Effects of diurnal variation on the Test of Variables of Attention performance in young adults with attention-deficit/hyperactivity disorder

The Test of Variables of Attention (TOVA) is a continuous performance test that assesses attention, impulsivity, and processing speed. Continuous performance tests are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children and adults. TOVA norms are based on a morning administration, and any TOVA administered after 1:00 p.m. is flagged as potentially invalid. Whereas the testing time recommendations make sense for pediatric samples, it is unclear whether they are appropriate for young adults, who typically show significant phase delay in their diurnal rhythms. The current study explores the impact of time of day on TOVA performance in young adults with ADHD. Participants were randomly assigned to either morning or afternoon administration. We found no significant diurnal variation in TOVA performance. We also found no interaction between diurnal preference and time of day of administration. Night owls endorsed more inattention symptoms on a self-report measure than more intermediate individuals but actually made significantly fewer omission (inattention) errors on the TOVA. Self-reported symptoms of inattention showed moderate, significant correlations with various TOVA performance indices. Self-reported symptoms of hyperactivity and impulsivity, however, showed no relationship to TOVA performance. These results suggest that the TOVA can be administered to adults with ADHD outside of the hours recommended in the manual without significantly compromising the interpretative validity of test score interpretation. Thus, a TOVA report that is consistent with ADHD should not be dismissed simply because it was administered in the late afternoon.     

Reinforcing effects of caffeine in coffee and capsules.

In a residential research ward the reinforcing and subjective effects of caffeine were studied under double-blind conditions in volunteer subjects with histories of heavy coffee drinking. In Experiment 1, 6 subjects had 13 opportunities each day to self-administer either a caffeine (100 mg) or a placebo capsule for periods of 14 to 61 days. All subjects developed a clear preference for caffeine, with intake of caffeine becoming relatively stable after preference had been attained. Preference for caffeine was demonstrated whether or not preference testing was preceded by a period of 10 to 37 days of caffeine abstinence, suggesting that a recent history of heavy caffeine intake (tolerance/dependence) was not a necessary condition for caffeine to function as a reinforcer. In Experiment 2, 6 subjects had 10 opportunities each day to self-administer a cup of coffee or (on different days) a capsule, dependent upon completing a work requirement that progressively increased and then decreased over days. Each day, one of four conditions was studied: caffeinated coffee (100 mg/cup), decaffeinated coffee, caffeine capsules (100 mg/capsule), or placebo capsules. Caffeinated coffee maintained the most self-administration, significantly higher than decaffeinated coffee and placebo capsules but not different from caffeine capsules. Both decaffeinated coffee and caffeine capsules were significantly higher than placebo capsules but not different from each other. In both experiments, subject ratings of "linking" of coffee or capsules covaried with the self-administration measures. These experiments provide the clearest demonstrations to date of the reinforcing effects of caffeine in capsules and in coffee.     

Arousal and recognition memory: The effects of impulsivity,caffeine and time on task

Systematic changes in performance on memory tasks have been observed as a function of the number of prior items or lists learned. In an attempt to determine whether this was an ‘attentional’ phenomenon the effect of arousal (as indexed by Impulsivity and manipulated by caffeine) on memory performance was examined. One hundred college students were given either 4 mg of caffeine/kg body weight or a placebo and then shown four lists (two 24-item and two 80-item) of four letter words. A forced-choice recognition test for the last 20 items was given immediately after each list. The performance of the high impulsives who were given a placebo (least aroused subjects) declined as a function of the number of prior lists learned. Low impulsives (more aroused) showed significantly less decline. Caffeine significantly improved recognition memory especially on the final lists. Decrements in memory performance, as a function of number of prior litsts, are thus reduced by the same variables which reduce vigilance decrements. It is suggested that common explanations will be required.     

Performance of chronotypes on memory tests during the morning and the evening shifts

Memory consists of several phases or processes that can be influenced by many factors, including the individual's circadian rhythm and the time of day at which tests are performed. The present objective was to evaluate the performance on memory tests of different chronotypes during the morning and the evening shifts. Subjects (21 men and 26 women, between the ages of 20 and 35 yr.) were evaluated for memory and metamemory differences in the morning and in the afternoon, using a battery of neuropsychological tests composed of the Word List with Emotional Content, Visual Memory, Scale-Semantic Memory, Digit Span, Word-Pairs Associated, Verbal Fluency Test, and Metamemory questionnaire. In the evening shift, there was a statistical difference among chronotypes on the Word List with Neutral Content and on the Verbal Fluency Test. In the morning, there were no statistically significant differences; however, the morning-type subjects had higher scores on the metamemory tests (p<.01), while the evening-type subjects had higher scores in the afternoon (p<.01). In spite of their perception, on Word-Pairs Associated and Word List with Emotional Content, the subjects, independently of their chronotype, showed better performance by the evening than by the morning shift. These results highlight the importance of controlling the shift of day and chronotype in studies with the objective of exploration of human performance.     

Time of day and the representation of text

This article reports an experiment to investigate the idea that time-of-day differences in memory for text are related to type of text processing that is carried out at different times of day. In particular, it was hypothesized that subjects tested in the morning tend to retain more of the exact wording of the text, whereas those tested in the afternoon are more likely to produce a meaning-based representation. The results of a recognition test showed that, in agreement with other studies, immediate text memory is better in the morning than in the afternoon. As predicted, the subjects tested in the morning better remembered the exact wording of the original passages. However, the idea that memory for meaning is better in the afternoon than the morning was not supported by the data. The results suggest that subjects at both times of day produce a meaning-based representation of the text but, in the morning, this representation is supported by good verbatim memory, enabling accurate recall of the text at that time.     

Time of day and the representation of text

This article reports an experiment to investigate the idea that time-of-day differences in memory for text are related to type of text processing that is carried out at different times of day. In particular, it was hypothesized that subjects tested in the morning tend to retain more of the exact wording of the text, whereas those tested in the afternoon are more likely to produce a meaning-based representation. The results of a recognition test showed that, in agreement with other studies, immediate text memory is better in the morning than in the afternoon. As predicted, the subjects tested in the morning better remembered the exact wording of the original passages. However, the idea that memory for meaning is better in the afternoon than the morning was not supported by the data. The results suggest that subjects at both times of day produce a meaning-based representation of the text but, in the morning, this representation is supported by good verbatim memory, enabling accurate recall of the text at that time.     

Representation of time in time-place learning

Ordinal, interval, and circadian mechanisms of solving a time-place task were tested. Rats searched for food twice in the morning and once in the afternoon (Group AB-C, n = 5) or once in the morning and twice in the afternoon (Group A-BC, n = 5) in a box with four food troughs. The location of the food depended on the time of day in a 12:12-h light:dark cycle. Acquisition was documented by food-site inspections at the correct locations prior to food availability. On nonrewarded probes, the time of the middle search (B) was shifted late (for Group AB-C) or early (for Group A-BC). The rats visited Location B at chance, contrary to an ordinal mechanism. When the posttesting meal and light-dark transitions were omitted, the rats visited correct locations with impaired performance but at above-chance levels on nonrewarded probes. The results are consistent with interval and circadian representations of time.     

Three consecutive nights of sleep loss: Effects of morning caffeine consumption on subjective sleepiness/alertness,reaction time and simulated driving performance

Caffeinated products are often consumed as a popular countermeasure to the effects of sleep loss. However, the efficacy of caffeine to exert these effects after consecutive nights of sleep loss is poorly understood. The aim of this study was to investigate the effects of three consecutive nights of restricted sleep and morning caffeine consumption on subjective ratings of sleepiness/alertness, reaction time, and simulated driving performance. Twenty healthy, habitual caffeine consumers (11 females; age: 23.3 ± 5.7 y; BMI: 22.3 ± 3.5 kg⋅m⁻²; caffeine intake: 204 ± 89 mg⋅day⁻¹; Mean ± SD) who had normal sleeping patterns (≥8 h⋅night⁻¹) participated in this double-blind, placebo-controlled, randomised study. Following one night of normal sleep (≥8 h time in bed (TIB)), participants underwent three consecutive nights of restricted sleep (5 h TIB). Participants received caffeine (200 mg; n = 10) or placebo (n = 10) capsules each morning and all participants received caffeine (100 mg) capsules each afternoon. Subjective ratings of alertness, concentration and tiredness were measured before and 1 h after morning capsule administration. Choice Reaction Time (CRT) was examined 1 h after morning capsule administration, with response speed and accuracy as outcome variables. Driving performance was assessed using a 30 min simulated driving task, with lateral (standard deviation of lane position [SDLP]; total number of line crossings [LC]) and longitudinal (standard deviation of speed [SDSP]) measures of vehicle control as outcome variables. Alertness and concentration significantly decreased, and tiredness increased across the three days of sleep loss. Caffeine only marginally alleviated these effects. No differences were observed between treatments or across trial days for response speed and accuracy on the CRT task. Likewise, no significant differences were observed between groups or across trial days for any measures of simulated driving performance. Overall, results from this study indicate that three consecutive days of sleep loss influence subjective ratings of alertness, concentration and tiredness, but does not alter CRT or simulated driving performance. Caffeine may alleviate some of the negative subjective effects imposed by restricted sleep, but the efficacy of caffeine to attenuate performance changes in CRT and driving performance were unable to be observed.     

Episodic priming and memory for temporal source: event-related potentials reveal age-related differences in prefrontal functioning.

Event-related potentials (ERPs) were recorded from young (M = 25) and older (M = 71) adults during a recognition memory paradigm that assessed episodic priming. Participants studied two temporally distinct lists of sentences (each with two unassociated nouns). At test, in response to the nouns, participants made old-new, followed by remember (context)-know (familiarity) and source (i.e., list) judgments. Both young and older adults showed equivalent episodic priming effects. However, compared to the young adults, the older adults showed a greater source performance decrement than item memory performance decrement. Both age groups showed equivalent posterior-maximal old-new ERP effects. However, only the young produced a frontal-maximal, late onset old-new effect that differed as a function of subsequent list attribution. Because source memory is thought to be mediated by prefrontal cortex, we conclude that age-related memory differences may be due to a deficit in a prefrontal cortical system that underlies source memory and are not likely to be due to an age-related decline in episodic priming.     

Time of day affects episodic memory in older adults

The neuropsychological test scores of 2030 cognitively normal older adults were examined to evaluate performance patterns as they related to time of day (TOD) at which testing was initiated. Multiple regression analyses were used to examine the association of TOD with scores on seven neuropsychological tests used in the clinical evaluation of dementia. Episodic memory performance was significantly related to TOD, while memory span and verbal fluency were not. Best performance occurred during early morning hours and late afternoon; worst performance occurred mid-day (i.e., noon). These findings may have implications for clinical assessment, the design of research on dementia, and the daily functioning of older adults.     

Effects of diurnal variation and caffeine consumption on Test of Variables of Attention (TOVA) performance in healthy young adults

The Test of Variables of Attention (TOVA) is a continuous performance test (CPT) that assesses attention, impulsivity, and processing speed. CPTs are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children, but more young adults are being assessed for ADHD as well. The TOVA norms are based on a standardization sample that was tested early in the day, and any TOVA administered after 1:00 p.m. will be flagged as potentially invalid. Whereas the testing time recommendations make sense for pediatric samples, it is unclear whether they are appropriate for young adults in college, who typically show significant phase delay in their diurnal rhythms. In addition, many college students consume large amounts of caffeine, and it is unclear how caffeine consumption affects TOVA performance. The current study examined the impact of time of day, self-reported diurnal preference, and caffeine consumption on TOVA performance in a double-blind, placebo-controlled experiment with healthy college students. There was evidence of diurnal variation on average response time and impulsivity but not on overall ADHD score, with participants tested in the afternoon responding faster but making more commission errors than did participants tested in the morning. Caffeine consumption led to significantly faster response times, but only for participants who typically consumed relatively little caffeine. We conclude that the TOVA can be administered to young adults outside the recommended time constraints without compromising the validity of test score interpretation but that the caffeine consumption of participants should be closely monitored.     

Time of Day Affects Episodic Memory in Older Adults*

ABSTRACT

The neuropsychological test scores of 2,030 cognitively normal older adults were examined to evaluate performance patterns as they related to time of day (TOD) at which testing was initiated. Multiple regression analyses were used to examine the association of TOD with scores on seven neuropsychological tests used in the clinical evaluation of dementia. Episodic memory performance was significantly related to TOD, while memory span and verbal fluency were not. Best performance occurred during early morning hours and late afternoon; worst performance occurred mid-day (i.e., noon). These findings may have implications for clinical assessment, the design of research on dementia, and the daily functioning of older adults.     

Time of day and processing strategy in free recall

Consistent effects of time of day have been observed in digit span/sequence performance, and in the immediate memory for information presented in prose. However, studies using syntactically unstructured word lists have yielded inconsistent results. Three experiments were conducted that examined the free recall of 15 word lists. In all three, immediate recall from the pre-recency positions was found to be superior in the morning to the afternoon. This superiority disappeared after a 20-min delay (Experiment 1) and under articulatory suppression (Experiment III), but was unaffected by a manipulation that equated recall order (Experiment II). Immediate recall from the recency positions showed a W-shaped trend over the day (Experiment I) that might account for the inconsistencies previously reported. It is suggested that the changes in recall from the pre-recency positions may reflect a decrease in maintenance, and increase in elaboration, over the day. Such a change in processing strategy could itself reflect an increase in attentional selectivity associated with the changes in basal arousal level commonly held to occur over the day.     

Text memory and integration at different times of day

This paper reports an experiment that explored whether the extent to which the ideas in a text are integrated changes over the day. In order to monitor integration, a task used by Wilkes, Alred and Al-Ahmar (1983) was adopted. The assumption underlying the task was that information that is inconsistent with respect to preceding information in a text will be remembered differently from information that is not inconsistent. Obviously, such selective remembering cannot occur if the information in the text is not integrated, so the degree to which differential remembering occurs can be taken as an index of degree of integration. Although the predicted differences in degree of integration between morning and afternoon subjects were not confirmed, the morning superiority effect in text recall was replicated, and it was demonstrated that this superiority arose because of the morning subjects' better memory for the exact wording of the text. In addition, subjects showed different types of recall error at the two times of day. These errors are discussed in relation to subjects' hypothesized changes in strategy over the day.     

The relationship between morningness–eveningness, time-of-day, speed of information processing, and intelligence

Morningness–Eveningness refers to individual differences in circadian phase position of spontaneous sleep–wake rhythms and to subject alertness. There is some evidence indicating that performance on cognitive tasks may be influenced by Morningness–Eveningness and time-of-day. Given the potential importance of such a finding for the assessment of cognitive ability we conducted a study assessing the relationship between Morningness–Eveningness, time-of-day, and performance on the Multidimensional Aptitude Battery IQ (MAB-IQ) and Inspection Time (IT) task. Twenty male and 50 female participants classified according to their scores on the Morningness–Eveningness dimension (Horne & Östberg, 1976) were administered the MAB and IT tasks in the morning (0900 h) and in the late afternoon (1500 h). No significant effect of time of testing, and Morningness–Eveningness was observed except for the Spatial subtest of the MAB. Morning Type-participants performed significantly worse in the morning session in Spatial subtest and better in the late afternoon session and Evening Type-participants performed significantly better in the morning than in the late afternoon session. These results do not support the hypothesis that there is a reliable relationship between Morningness–Eveningness, time-of-day and cognitive ability.     

Synchrony effects in automatic and controlled retrieval

Using a speeded retrieval procedure, we investigated time-of-day effects in automatic and controlled retrieval. Morning-type adults were tested at either peak (early morning) or off-peak (late afternoon) times on a speeded implicit (Experiment 1) or explicit (Experiment 2) stem completion task. In Experiment 1, retrieval strategies were identified by changes in response speed between a practice phase with rapid retrieval and an implicit memory test phase. Performance based on controlled retrieval (shown by slowdown participants) showed more priming at peak than at off-peak times of day, a finding confirmed in Experiment 2, in which the participants were given intentional retrieval instructions when the materials switched. In contrast, performance based on automatic retrieval (shown by nonslowdown participants) did not differ across peak and off-peak times. The finding suggests a robust synchrony effect in controlled retrieval, but not in automatic retrieval, which does not appear to vary across the day.