Karolien Smets | KU Leuven (original) (raw)
Papers by Karolien Smets
Frontiers in Human Neuroscience, 2013
As a result of the representation of numerosities, more accurate and faster discrimination betwee... more As a result of the representation of numerosities, more accurate and faster discrimination between two numerosities is observed when the distance between them increases. In previous studies, the comparison and same-different task were most frequently used to investigate this distance effect. Recently, it was questioned whether the non-symbolic distance effects derived from these tasks originate at the same level. In the current study, we examined the behavioral and neural distance effects of the comparison and same-different task to assess potential differences between both tasks. Participants were first year university students. Each participant completed both tasks, while their reaction time, accuracy and brain activity on predefined components was measured. The early N1-P2p transition and the P2p component on temporo-occipital (TO) and inferior parietal (IP) electrode groups were considered, as well as the late P3 component on a central (C) electrode group. The results showed that the behavioral distance effects from both tasks were comparable, although participants' performance was worse on the same-different task. The neural results revealed similar effects of distance on the mean amplitudes for the early components for both tasks (all p s < 0.02) and an additional effect of task difficulty on the mean amplitudes of these components. Similar as in previous studies, we found a (marginally) significant increase in mean amplitude of the later P3 component with increasing distance for the comparison (p = 0.07), but not for the same-different task. Apparently, the initial stages of number processing are comparable for both tasks, but an additional later stage is only present for the comparison task. The P3 effect would be indicative of this decisional stage, which was previously proposed to underlie the comparison distance effect (CDE).
Journal of Cognitive Psychology, 2015
Numerosity estimation and comparison tasks are often used to measure the acuity of the approximat... more Numerosity estimation and comparison tasks are often used to measure the acuity of the approximate number system (ANS), a mechanism which allows extracting numerosity from an array of dots independently from several visual cues (e.g. area extended by the dots). This idea is supported by studies showing that numerosity can be processed while these visual cues are controlled for. Different methods to construct dot arrays while controlling their visual cues have been proposed in the past. In this paper, these methods were contrasted in an estimation and a comparison task. The way of constructing the dot arrays had little impact on estimation. In contrast, in the comparison task, participants' performance was significantly influenced by the method that was used to construct the arrays of dots, indicating better performance when the visual cues of the dot arrays (partly) co-varied with numerosity. The present study therefore shows that estimates of ANS acuity derived from comparison tasks are inconsistent and dependent on how the stimuli are constructed. This makes it difficult to compare studies which utilised different methods to construct the dot arrays in numerosity comparison tasks. In addition, these results question the currently held view of the ANS as capable of robustly extracting numerosity independently from visual cues.
Psychologica Belgica, 2012
Recent studies have shown that subliminal priming effects can be of a semantic nature. However, t... more Recent studies have shown that subliminal priming effects can be of a semantic nature. However, the question remains how strong this kind of priming will prove to be. In the present study we investigated whether truly semantic unconscious priming only occurs for prime-target pairs that are strongly semantically related (e.g., cat-DOG) or whether priming effects can also be observed for pairs that are less semantically related (e.g., ant-DOG). A typical masked priming paradigm, with word primes and picture targets, was used and the relatedness between prime and target was manipulated. The results showed that prime-target relatedness significantly moderated the effects. A priming effect was only found for the strongly related prime-target pairs. This indicates that semantic subliminal priming requires a sufficient amount of semantic relatedness between prime and target, rendering it as sensitive to this semantic factor as supraliminal priming.
Emotion, 2014
Research has shown that emotional events are remembered better than neutral events, but might als... more Research has shown that emotional events are remembered better than neutral events, but might also elicit an increase in false memories. The present study was designed to disentangle the influences of valence and arousal on event memory in the misinformation paradigm. Participants were shown six types of photographs (positive with high/low arousal, negative with high/low arousal, ambiguous, neutral), after which half of them were exposed to misleading information. A recognition test assessed memory for both correct and false central and peripheral details. Negative and ambiguous events elicited fewer correct and more false memories for peripheral details than positive and neutral events, regardless of previous exposure to misinformation. Arousal improved memory for correct central details, and both negative valence and arousal inhibited control participants' tendency to endorse false central details. The power of emotion was overruled by the power of suggestion, however, as the latter effect disappeared with previous exposure to misinformation. Results are discussed in the light of earlier research on emotion and cognition, recent motivational theories, and implications for forensic practice.
Acta Psychologica, 2014
Reasoning with non-symbolic numerosities is suggested to be rooted in the Approximate Number Syst... more Reasoning with non-symbolic numerosities is suggested to be rooted in the Approximate Number System (ANS) and evidence pointing to a relationship between the acuity of this system and mathematics is available. In order to use the acuity of this ANS as a screening instrument to detect future math problems, it is important to model ANS acuity over development. However, whether ANS acuity and its development have been described accurately can be questioned. Namely, different tasks were used to examine the developmental trajectory of ANS acuity and studies comparing performances on these different tasks are scarce. In the present study, we examined whether different tasks designed to measure the acuity of the ANS are comparable and lead to related ANS acuity measures (i.e., the concurrent validity of these tasks). We contrasted the change detection task, which is used in infants, with tasks that are more commonly used in older children and adults (i.e., comparison and same-different tasks). Together, our results suggest that ANS acuity measures obtained with different tasks are not related. This poses serious problems for the comparison of ANS acuity measures derived from different tasks and thus for the establishment of the developmental trajectory of ANS acuity.
Frontiers in Human Neuroscience, 2013
As a result of the representation of numerosities, more accurate and faster discrimination betwee... more As a result of the representation of numerosities, more accurate and faster discrimination between two numerosities is observed when the distance between them increases. In previous studies, the comparison and same-different task were most frequently used to investigate this distance effect. Recently, it was questioned whether the non-symbolic distance effects derived from these tasks originate at the same level. In the current study, we examined the behavioral and neural distance effects of the comparison and same-different task to assess potential differences between both tasks. Participants were first year university students. Each participant completed both tasks, while their reaction time, accuracy and brain activity on predefined components was measured. The early N1-P2p transition and the P2p component on temporo-occipital (TO) and inferior parietal (IP) electrode groups were considered, as well as the late P3 component on a central (C) electrode group. The results showed that the behavioral distance effects from both tasks were comparable, although participants' performance was worse on the same-different task. The neural results revealed similar effects of distance on the mean amplitudes for the early components for both tasks (all p s < 0.02) and an additional effect of task difficulty on the mean amplitudes of these components. Similar as in previous studies, we found a (marginally) significant increase in mean amplitude of the later P3 component with increasing distance for the comparison (p = 0.07), but not for the same-different task. Apparently, the initial stages of number processing are comparable for both tasks, but an additional later stage is only present for the comparison task. The P3 effect would be indicative of this decisional stage, which was previously proposed to underlie the comparison distance effect (CDE).
Journal of Cognitive Psychology, 2015
Numerosity estimation and comparison tasks are often used to measure the acuity of the approximat... more Numerosity estimation and comparison tasks are often used to measure the acuity of the approximate number system (ANS), a mechanism which allows extracting numerosity from an array of dots independently from several visual cues (e.g. area extended by the dots). This idea is supported by studies showing that numerosity can be processed while these visual cues are controlled for. Different methods to construct dot arrays while controlling their visual cues have been proposed in the past. In this paper, these methods were contrasted in an estimation and a comparison task. The way of constructing the dot arrays had little impact on estimation. In contrast, in the comparison task, participants' performance was significantly influenced by the method that was used to construct the arrays of dots, indicating better performance when the visual cues of the dot arrays (partly) co-varied with numerosity. The present study therefore shows that estimates of ANS acuity derived from comparison tasks are inconsistent and dependent on how the stimuli are constructed. This makes it difficult to compare studies which utilised different methods to construct the dot arrays in numerosity comparison tasks. In addition, these results question the currently held view of the ANS as capable of robustly extracting numerosity independently from visual cues.
Psychologica Belgica, 2012
Recent studies have shown that subliminal priming effects can be of a semantic nature. However, t... more Recent studies have shown that subliminal priming effects can be of a semantic nature. However, the question remains how strong this kind of priming will prove to be. In the present study we investigated whether truly semantic unconscious priming only occurs for prime-target pairs that are strongly semantically related (e.g., cat-DOG) or whether priming effects can also be observed for pairs that are less semantically related (e.g., ant-DOG). A typical masked priming paradigm, with word primes and picture targets, was used and the relatedness between prime and target was manipulated. The results showed that prime-target relatedness significantly moderated the effects. A priming effect was only found for the strongly related prime-target pairs. This indicates that semantic subliminal priming requires a sufficient amount of semantic relatedness between prime and target, rendering it as sensitive to this semantic factor as supraliminal priming.
Emotion, 2014
Research has shown that emotional events are remembered better than neutral events, but might als... more Research has shown that emotional events are remembered better than neutral events, but might also elicit an increase in false memories. The present study was designed to disentangle the influences of valence and arousal on event memory in the misinformation paradigm. Participants were shown six types of photographs (positive with high/low arousal, negative with high/low arousal, ambiguous, neutral), after which half of them were exposed to misleading information. A recognition test assessed memory for both correct and false central and peripheral details. Negative and ambiguous events elicited fewer correct and more false memories for peripheral details than positive and neutral events, regardless of previous exposure to misinformation. Arousal improved memory for correct central details, and both negative valence and arousal inhibited control participants' tendency to endorse false central details. The power of emotion was overruled by the power of suggestion, however, as the latter effect disappeared with previous exposure to misinformation. Results are discussed in the light of earlier research on emotion and cognition, recent motivational theories, and implications for forensic practice.
Acta Psychologica, 2014
Reasoning with non-symbolic numerosities is suggested to be rooted in the Approximate Number Syst... more Reasoning with non-symbolic numerosities is suggested to be rooted in the Approximate Number System (ANS) and evidence pointing to a relationship between the acuity of this system and mathematics is available. In order to use the acuity of this ANS as a screening instrument to detect future math problems, it is important to model ANS acuity over development. However, whether ANS acuity and its development have been described accurately can be questioned. Namely, different tasks were used to examine the developmental trajectory of ANS acuity and studies comparing performances on these different tasks are scarce. In the present study, we examined whether different tasks designed to measure the acuity of the ANS are comparable and lead to related ANS acuity measures (i.e., the concurrent validity of these tasks). We contrasted the change detection task, which is used in infants, with tasks that are more commonly used in older children and adults (i.e., comparison and same-different tasks). Together, our results suggest that ANS acuity measures obtained with different tasks are not related. This poses serious problems for the comparison of ANS acuity measures derived from different tasks and thus for the establishment of the developmental trajectory of ANS acuity.