Experimental Psychology Society

Forensic psychologists use cognitive-neuroscience principles to detect concealed information in individuals, which can help to identify perpetrators. One method, the Concealed Information Test (CIT), relies on the physiological response (orienting response) to familiar crime-related information, in particular items with strong emotional connections, such as the weapon used in a crime. However, traditional CITs can be compromised by countermeasures, such as wiggling one’s toes during irrelevant items to mask orienting responses to the crime-related items.<br/><br/>In our study, we tested a non-traditional CIT based on rapid serial visual presentation (RSVP), which is believed to be more resistant to countermeasures. This method rapidly and sequentially presents visual stimuli, including familiar and irrelevant items. We measured participants’ pupil size, microsaccades (small eye movements), eye blinks, and electrical brain activity to test if we could distinguish familiar (our proxy for concealed information) and irrelevant items based on these measures. We found that using pupil size and electrical brain activity, we could indeed detect concealed information above chance. However, precision was too low to reliably detect concealed information in all individual participants. We also tested another paradigm, based on serial sequential stimulus movement (SSSM), which uses pupil size and gaze position to detect concealed information. The detection rate for individuals was higher in this paradigm compared to the RSVP-based CIT, but still below the reliability required for individual classification. We conclude that further refinement is needed before the currently tested CITs can be used in forensic practice.

Working memory is akin to holding onto a phone-number until it’s dialled. But,<br/>not all digits have the same functional role here while each digit is individually<br/>dialled whereas others are just retained. Our research investigated how the<br/>shifting functional roles of memories influence our brain states, by using a<br/>unique method to study low or non-activity brain states. In Chapter 2, we<br/>probed memory when only one of the two memorized colours would be<br/>reported. Surprisingly, both colours, including the unnecessary one, were<br/>detectable in brain signals. Crucially, the brain states of these two colours<br/>differed, reflecting functional differences. With a similar set-up in Chapter 3 we<br/>studied memory for orientations. Importantly we asked participants to rotate<br/>the cued orientation and use only rotation-product to judge a new probe.<br/>Astonishingly, brain signals represented both the cued and the rotated<br/>memory, but not the non-rotated one. These results suggest that memories<br/>can persist in low/non-active brain states even after they lose their functional<br/>role. In Chapter 4, pre-learned orientations were used to judge the tilt of a<br/>probe. Orientations were either visually shown or were cued by an auditory<br/>tone. In both cases the brain states were similar, although neural-connectivity<br/>differed, as evidence indicated connections between visual and auditory<br/>regions when a tone was presented. Overall results show that brain states<br/>change when functional roles change but the states vary more than just<br/>‘actively guiding behaviour’ and ‘idly retained’. Different response strategies<br/>of the participants may also contribute to this.

Four minutes at the bus stop can feel like an eternity, while time flies when we are watching an enjoyable movie. Our sense of time is very elastic. In this thesis, we investigate how people use previous experiences to predict how long something will last and when something will happen. We show that experiences in memory have a direct influence on the way we experience time. When participants estimated a duration, we observed a faster build-up of brain activity if they had just estimated shorter durations. The brain does not seem to work like a static stopwatch, but instead creates active expectations based on previous experiences. Does this mechanism of expectations still work when we are doing something else, for example, when we are listening to music while working? Our results show that people perceive drum rhythms in a musical way, even when they are performing another task. We observed that the size of the pupil increased when a beat was omitted from the rhythm. And the more important the beat, the larger the pupil. Thus, our eyes reveal how musical we subconsciously are. All in all, this thesis shows that time can be seen as an inherent part of brain processes that adapt to a dynamically changing world.

It is well-established that young adults encode letter position flexibly during natural reading. However, given the visual changes that occur with normal aging, it is important to establish whether letter position coding is equivalent across adulthood. In 2 experiments, young (18–25 years) and older (65+ years) adults’ were recorded while reading sentences with words containing transposed adjacent letters. Transpositions occurred at beginning (rpoblem), internal (porblem), or end (problme) locations in words. In Experiment 1, these transpositions were present throughout reading. By comparison, Experiment 2 used a gaze-contingent paradigm such that once the reader’s gaze moved past a word containing a transposition, this word was shown correctly and did not subsequently change. Both age groups showed normal levels of comprehension for text including words with transposed letters. The pattern of letter transposition effects on eye movements was similar for the young and older adults, with greater increases in reading times when external relative to internal letters were transposed. In Experiment 1, however, effects of word beginning transpositions during rereading were larger for the older adults. In Experiment 2 there were no interactions, confirming that letter position coding is similar for both age groups at least during first-pass processing of words. These findings show that flexibility in letter position encoding during the initial processing of words is preserved across adulthood, although the interaction effect in rereading in Experiment 1 also suggests that older readers may use more stringent postlexical verification processes, for which the accuracy of word beginning letters is especially important.

BackgroundWorking Memory Capacity (WMC) is thought to be related to executive control and focused memory search abilities. These two hypotheses make contrasting predictions regarding the effects of retrieval on forgetting. Executive control during memory retrieval is believed to lead to retrieval induced forgetting (RIFO) because inhibition of competing memory traces during retrieval renders them temporarily less accessible. According to this suggestion, superior executive control should increase RIFO. Alternatively, superior focused search abilities could diminish RIFO, because delimiting the search set reduces the amount of competition between traces and thus the need for inhibition. Some evidence suggests that high WMC is related to more RIFO, which is inconsistent with the focused search hypothesis.Methodology/Principal FindingsUsing the RIFO paradigm, we created distinct and overlapping categories to manipulate the amount of competition between them. This overlap increased competition between some categories while exclusive use of weak exemplars ensured negligible effects of output interference and integration.Low WMC individuals exhibited RIFO within and between overlapping categories, indicating the effect of resolving competition during retrieval. High WMC individuals only exhibited between-category RIFO, suggesting they experienced reduced competition resolution demands. Low WMC Individuals exhibited the strongest RIFO and no retrieval benefits when interference resolution demands were high.Conclusions/SignificanceOur findings qualify the inhibitory explanation for RIFO by incorporating the focused search hypothesis for materials that are likely to pose extraordinary challenges at retrieval. The results highlight the importance of considering individual differences in retrieval-induced effects and qualify existing models of these effects.

Abstract Jones &amp; Love (J&amp;L) suggest that Bayesian approaches to the explanation of human behavior should be constrained by mechanistic theories. We argue that their proposal misconstrues the relation between process models, such as the Bayesian model, and mechanisms. While mechanistic theories can answer specific issues that arise from the study of processes, one cannot expect them to provide constraints in general.

This study presents preliminary electroencephalogram (EEG) data of children with Developmental Coordination Disorder (DCD) who executed a mental hand rotation paradigm similar to that described by Wilson and colleagues, who sought to test whether children with DCD have difficulties generating an accurate internal model of an intended action. Behavioural, neurological and neuro-imaging (positron emission tomography) data suggest that hand rotation is a valid and reliable probe to investigate motor imagery. Motor imagery is the ability to mentally simulate the movement of a limb. Motor imagery tasks may be used to measure deficiencies in the ability to generate an accurate internal representation (or internal model) of an intended movement; the internal model is open to conscious awareness through imagery while execution of the overt movement plan has been inhibited. Motor imagery is thus an excellent means by which the structure of movement representations can be investigated.