One of the first descriptions of Psychology hails from the now famous Edwin Smith Papyrus from Ancient Egypt. The papyrus described nearly 50 conditions of trauma and wound care, including the first speculations on the human brain. Ancient Greek philosophers such as Plato and Aristotle developed their ideas about the psyche (psuchẽ), providing the namesake of modern Psychology. In 1879, Wilhelm Wundt opened the first laboratory dedicated exclusively to understanding consciousness and mental processes. Nearing the turn of the century, Sigmund Freud developed psychoanalysis. Freud later gained immense fame for his Interpretation of Dreams which he published in 1900, and later when he published Three Essays on the Theory of Sexuality in 1905. Modern Psychology today has differentiated into a number of disciplines and applications, including modern cognitive psychology which strives to understand deeply complex issues such as memory, perception, and thought. From the first papyrus markings to modern psychology, we are continuing to learn about the human mind.
At the University of New Brunswick, PhD student Corinna McFeaters is working to explore some of these questions by delving into research examining how people perceive time. McFeaters began her journey towards a PhD in Experimental Psychology as a student initially studying music business and songwriting. Following her Bachelor’s of Music at Berklee College of Music, she completed a graduate degree in Clinical Mental Health Counselling with a concentration in holistic therapies at Lesley University. Once McFeaters finished her degree, she worked as a counsellor for a number of years prior to returning to school to complete a PhD at UNB focusing on the research skills that were absent from her clinical training.
Difficulties of Studying the Mind
McFeaters has always had an interest in how the mind works and how basic cognitive processes such as attention, memory, and perception influence human experience and behaviour. Along with Dr. Daniel Voyer, McFeaters began studying time perception. There are a vast number of influences that can change the way we perceive and process stimuli, which can cause difficulty when attempting to investigate time perception. The many variables include sensory modality, the placement of response options, attention, memory factors, stimulus type, intensity, and others. Additionally, task demands can affect how we process information. McFeaters’ research has focused on the estimation of the duration, but some time perception studies have focused on different types of tasks, such as detecting a gap in a sound, which can produce different, and sometimes contradictory, results. All of these confounding variables can create a problem when trying to isolate time perception without other factors influencing the results.
To illustrate an example, in one line of research, Voyer’s lab has been studying auditory laterality in time perception. Some cognitive processes tend to be more dominant in one hemisphere of the brain, a concept known as laterality. For example, language is usually handled predominantly by the left hemisphere, while visuospatial tasks are processed mostly in the right hemisphere. Because of the way our brain is organized, a stimulus presented to one ear is primarily processed by the opposite (contralateral) hemisphere, so if one ear is more accurate, it suggests that the opposite hemisphere is better at the task. Thus, participants are presented a stimulus to only one ear at a time, and they are asked to judge whether the duration is closer to a short example or a long example, called anchor stimuli.
One of the first questions McFeaters & Voyer attempted to resolve was whether the presence of emotion or the placement of response options may have affected the results of a series of experiments by Voyer & Reuangrith who found that duration was estimated more accurately by the right hemisphere, contrary to the findings of other similar experiments in this area. Evidence suggests the right hemisphere of the brain is in control of emotion, so Voyer and Reuangrith’s use of stimuli with an emotional component may have biased processing toward the right hemisphere. Additionally, how response options are arranged on the screen could have affected the findings. We form cognitive representations for concepts such as time and numeracy, and reading direction may influence how we form these representations. Left-to-right readers tend to construct mental timelines and number lines with smaller quantities on the left and larger quantities on the right. When response options match these mental representations, responses have been shown to be faster and more accurate. Because Voyer & Reuangrith only examined a short-on-the-left, long-on-the-right configuration, it was possible that responses were affected by how the response options were positioned.
McFeaters and Voyer observed that when the emotional aspect of the stimulus was removed, the participants responded to the stimulus the same way they had when the emotional aspect was present. Emotion had no effect on the results. Next, McFeaters & Voyer looked at how the response options were structured. When the response options were reversed, meaning that the long button was now placed on the left and the short button on the right, the results had reversed. The reversal of the results was unexpected, and it suggested that response placement is an important variable to consider when conducting this type of research. In an attempt to get a more definitive answer as to what causes response placement to affect the results in this type of experiment, McFeaters & Voyer have continued this research, investigating other orientations and types of response options. They discovered that when response options were placed one above the other, duration was judged similarly by both hemispheres. However, if a left/right placement was used, participants’ responses depended on the orientation of the response options. When short was on the left, a right hemisphere advantage was found, but when short was on the right, the left hemisphere was more accurate. This pattern held even if symbols were used instead of the words short and long. Additionally, to the surprise of McFeaters and Voyer, when only one option was presented in the middle of the screen and the participants could click anywhere else on the screen for the other option, results mirrored the left/right results because participants tended to create their own left/right response mapping by almost always clicking to the right of the central response option. McFeaters’ and Voyer’s results have shown that factors seemingly unrelated to the question that is being investigated can have a profound impact on the data that is obtained, and their research into the effect of response placement is ongoing.
More recently, McFeaters and Voyer have began investigating other factors affecting time perception, namely the influences of repetition and expectation (i.e., what we believe we will be presented with next). Generally, if one is exposed to a stimulus more than once, the subsequent time it is experienced, it will be perceived as shorter than the original stimuli. Recent exposure has also been demonstrated to produce a smaller neural signal on re-exposure. This decrease in neural signal is known as repetition suppression. There are various neurological reasons why repetition might decrease perceived duration. If we have just been exposed to a stimulus, our neurons cannot fire again for a brief period of time. Alternatively, on re-exposure, it might take less neural effort to identify it again. Another hypothesis is that it might be related to expectation: if you hear a sound or see something, for example, it is quite possible that you will encounter it again in short order. The second time it is experienced, there is less of a neural response because it is expected, which results in the observed repetition suppression.
Recent research has suggested that if repetition is expected, the repeated stimulus might not be perceived to be shorter. Expectation might actually expand subjective duration instead. McFeaters and Voyer have been working to replicate these findings and investigate the factors underlying this change in the way that the duration of repeated stimuli are judged. Their preliminary results suggest expected stimuli are perceived to be longer in duration, regardless of whether they are repeated or previously unencountered stimuli. Expectations seem to alter the way we perceive time.
Time is ubiquitous in our daily lives and it is remarkable that time itself, although such a simple concept, is seldom understood. All avenues of research in the area contribute to ever-growing literature showing the exceptional complexity of the brain. Growing on this knowledge in the future will help to further develop how science understands the working of the brain.
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