Ruth S. Ogden

Assessing the functional significance of ecstasy-related memory deficits using a virtual paradigm.

Previous research shows that the use of ecstasy results in working memory and executive impairments in some users. The present study sought to assess the functional significance of such deficits using a virtual reality task.

The role of executive functions in human prospective interval timing

Human timing is thought to be based on the output of an internal clock. Whilst the functioning of this clock is well documented, it is unclear which other cognitive resources may moderate timing. Brown (2006) and Rattat (2010) suggest that the central executive of working memory may be recruited during timing. However it seems likely that the fractionated executive component processes identified by Miyake et al. (2000) and Fisk and Sharp (2004) may differentially contribute to timing performance; further exploration of this was the aim of the present study. An interference paradigm was employed in which participants completed an interval production task, and tasks which have been shown to tap the four key executive component processes (shifting, inhibition, updating and access) under single and dual-task conditions. Comparison of single and dual-task performance indicated that timing always became more variable when concurrently performing a second task. Bidirectional interference only occurred between the interval production task and the memory updating task, implying that both tasks are competing for the same executive resource of updating. There was no evidence in the current study to suggest that switching, inhibition or access was involved in timing, however they may be recruited under more difficult task conditions.

Examining visual complexity and its influence on perceived duration

We investigated whether visual complexity of novel abstract patterns affects perceived duration. Previous research has reported that complex visual stimuli led to an underestimation of durations. However, to clarify the nature of the time estimation process, it is necessary to establish which component of image complexity, spatial or semantic, plays the critical role. Here we tested the impact of specific spatial properties. We used unfamiliar and abstract patterns made using black-and-white checkerboards in which the difference between stimuli was exclusively in configuration. Visual complexity was quantified by the GIF index based on a compression algorithm, which scanned the pattern in both horizontal and vertical directions. This metric correlated positively with subjective complexity (Experiment 1A). In the second study, we increased variability in the stimuli by changing the number of items across patterns while keeping overall size constant. A high positive correlation was found between objective and subjective complexity (r = 0.95) (Experiment 2A). In Experiments 1B and 2B, observers estimated pattern durations in seconds using a continuous scale. A multilevel linear analysis found that perceived duration was not predicted by visual complexity for either of the two sets of stimuli. These results provide new constraints to theories of time perception, hypothesizing that complexity leads to an underestimation of duration when it reduces attention to time.

The differential contribution of executive functions to temporal generalisation, reproduction and verbal estimation.

Evidence from dual-task studies suggests that executive resources are recruited during timing. However, there has been little exploration of whether executive recruitment is universal across temporal tasks, or whether different temporal tasks recruit different executive resources. The current study explored this further by examining how individual differences in updating, switching, inhibition and access affected performance on temporal generalisation, reproduction and verbal estimation tasks. It was found that temporal tasks differentially loaded onto different executive resources. Temporal generalisation performance was related to updating and access ability. Reproduction performance was related to updating, access and switching. Verbal estimation performance was only related to access. The results suggest that executive resources may be recruited when monitoring and maintaining multiple durations in memory at the same time, and when retrieving duration representations from long-term memory. The findings emphasise the need to consider timing behaviour as the product of a wide range of complex, integrated, cognitive systems, rather than as the output of a clock in isolation.

Are memories for duration modality specific

Four experiments examined the effects of encoding multiple standards in a temporal generalization task in the visual and auditory modalities both singly and cross-modally, using stimulus durations ranging, across different experiments, from 100 to 1,400 ms. Previous work has shown that encoding and storing multiple auditory standards of different durations resulted in systematic interference with the memory of the standard, characterized by a shift in the location of peak responding, and this result, from Ogden, Wearden, and Jones (2008), was replicated in the present Experiment 1. Experiment 2 employed the basic procedure of Ogden et al. using visual stimuli and found that encoding multiple visual standards did not lead to performance deterioration or any evidence of systematic interference between the standards. Experiments 3 and 4 examined potential cross-modal interference. When two standards of different modalities and durations were encoded and stored together there was also no evidence of interference between the two. Taken together, these results, and those of Ogden et al., suggest that, in humans, visual temporal reference memory may be more permanent than auditory reference memory and that auditory temporal information and visual temporal information do not mutually interfere in reference memory.

The effect of alcohol administration on human timing: A comparison of prospective timing, retrospective timing and passage of time judgements

Previous research suggests that human timing may be affected by alcohol administration. The current study aimed to expand on previous research by examining the effect of alcohol on prospective timing, retrospective timing and passage of time judgements. A blind between-subjects design was employed in which participants were either administered 0 g of alcohol per kilogramme of body weight (placebo), 0.4 g/kg (low dose) or 0.6g/kg (high dose). Participants completed four types of temporal task; verbal estimation and temporal generalisation, a retrospective timing task and a passage of time judgement task. A high dose of alcohol resulted in overestimations of duration relative to the low dose and placebo group in the verbal estimation task. A high dose of alcohol was also associated with time passing more quickly than normal. Alcohol had no effect on retrospective judgements. The results suggest that a high dose of alcohol increases internal clock speed leading to over-estimations of duration on prospective timing tasks, and the sensation of time passing more quickly than normal. The absence of an effect of alcohol on retrospective timing supports the suggestion that retrospective judgements are not based on the output of an internal clock.

The effect of pain and the anticipation of pain on temporal perception: A role for attention and arousal

The overestimation of the duration of fear-inducing stimuli relative to neutral stimuli is a robust finding within the temporal perception literature. Whilst this effect is consistently reported with auditory and visual stimuli, there has been little examination of whether it can be replicated using painful stimulation. The aim of the current study was, therefore, to explore how pain and the anticipation of pain affected perceived duration of time. A modified verbal estimation paradigm was developed in which participants estimated the duration of shapes previously conditioned to be associated with pain, compared to those not associated with pain. Duration estimates were significantly longer on trials in which pain was received or anticipated than on control trials. Slope and intercept analysis revealed that the anticipation of pain resulted in steeper slopes and greater intercept values than for control trials. The results suggest that increased arousal and attention, when anticipating and experiencing pain, result in longer perceived durations. The results are discussed in relation to internal clock theory and neurocognitive models of time perception.

The effect of facial attractiveness on temporal perception

Previous research suggests that feelings of fear, dislike, shame and sadness affect our perception of duration (Droit-Volet et al., 2004; Gil et al., 2009). The current study sought to expand our understanding of the variables which moderate temporal perception by examining whether the attractiveness of a face influenced its perceived duration. Participants completed a verbal estimation task in which they judged the duration of attractive, unattractive and neutral faces. The results showed that participants underestimated the duration of unattractive faces relative to attractive and neutral faces. Estimates of unattractive faces were also less accurate than those of the attractive and neutral faces. The results are consistent with Gil et al.s (2009) suggestion that the duration of disliked stimuli are underestimated relative to liked and neutral stimuli because they detract attention from temporal perception. Analysis of the slope and intercept of the estimation gradients supports Zakay and Blocks (1997) suggestion that reduced attention to time results in a multiplicative underestimation of duration.

More is still not better: Testing the perturbation model of temporal reference memory across different modalities and tasks

The ability of the perturbation model (Jones & Wearden, 2003) to account for reference memory function in a visual temporal generalization task and auditory and visual reproduction tasks was examined. In all tasks the number of presentations of the standard was manipulated (1, 3, or 5), and its effect on performance was compared. In visual temporal generalization the number of presentations of the standard did not affect the number of times the standard was correctly identified, nor did it affect the overall temporal generalization gradient. In auditory reproduction there was no effect of the number of times the standard was presented on mean reproductions. In visual reproduction mean reproductions were shorter when the standard was only presented once; however, this effect was reduced when a visual cue was provided before the first presentation of the standard. Whilst the results of all experiments are best accounted for by the perturbation model there appears to be some attentional benefit to multiple presentations of the standard in visual reproduction.

Vibrotactile timing: Are vibrotactile judgements of duration affected by repetitive stimulation?

Timing in the vibrotactile modality was explored. Previous research has shown that repetitive auditory stimulation (in the form of click-trains) and visual stimulation (in the form of flickers) can alter duration judgements in a manner consistent with a “speeding up” of an internal clock. In Experiments 1 and 2 we investigated whether repetitive vibrotactile stimulation in the form of vibration trains would also alter duration judgements of either vibrotactile stimuli or visual stimuli. Participants gave verbal estimates of the duration of vibrotactile and visual stimuli that were preceded either by five seconds of 5-Hz vibration trains, or, by a five-second period of no vibrotactile stimulation, the end of which was signalled by a single vibration pulse (control condition). The results showed that durations were overestimated in the vibrotactile train conditions relative to the control condition; however, the effects were not multiplicative (did not increase with increasing stimulus duration) and as such were not consistent with a speeding up of the internal clock, but rather with an additive attentional effect. An additional finding was that the slope of the vibrotactile psychometric (control condition) function was not significantly different from that of the visual (control condition) function, which replicates a finding from a previous cross-modal comparison of timing.