Bjørn Sætrevik | University of Bergen (original) (raw)

Papers by Bjørn Sætrevik

PLoS ONE, 2014

The use of nicotine in the form of &a... more The use of nicotine in the form of "snus" is substantial and increasing in some geographic areas, in particular among young people. It has previously been suggested that addictions may operate through a mechanism of attentional bias, in which stimuli representative of the dependent substance increase in salience, thus increasing the addictive behavior. However, this hypothesis has not been tested for the case of snus. The current experiment used a modified Stroop task and a dot-probe task to investigate whether 40 snus users show an attentional bias towards snus-relevant stimuli, compared to 40 non-snus users. There were no significant differences between the two groups on reaction times or accuracy on either Stroop or dot-probe task, thus failing to show an attentional bias towards snus-relevant stimuli for snus users. This could imply that other mechanisms may contribute to maintenance of snus use than for other addictions. However, this is the first experimental study investigating attentional bias in snus users, and more research is warranted.

Journal of Cognitive Engineering and Decision Making, 2013

The aim of this paper is to present a methodology where the extent of information sharing among t... more The aim of this paper is to present a methodology where the extent of information sharing among team members is used as an indicator of shared mental models (SMM) and situation awareness (SA). Data collection procedures and probe materials are described for two field experiments performed among emergency management teams in the hydrocarbon industry. Methods are suggested for calculating a “similarity index” by comparing a team member’s responses with the average response in the team or with the responses of the team member assumed to be best informed. It is argued that similarity to team average could be a measure of SMM, whereas similarity to the best-informed team member could be argued to be an indicator of SA. The degree of compliance in responding to the probes is reported, as is the degree to which the extent of shared information differed between the probe questions or according to team positions. Lessons learned from the data collection are summarized, and the applicability of the similarity index as a measure of SA is discussed. Some advantages of the current approach are presented, as are challenges and inherent assumptions in future applications of this approach.

Brain and Cognition, 2013

Sequences of events can affect selective attention either through proactive mechanisms, through r... more Sequences of events can affect selective attention either through proactive mechanisms, through reactive mechanisms, or through a combination of the two. The current study examined electrophysiological responses to both prime and target stimuli in a primed dichotic listening task. Each trial presented a distractor prime syllable followed by two simultaneous syllables, and participants were asked to report one of the simultaneous syllables. Trials where the participant reported the non-primed syllable showed more negative event-related potentials at prime presentation, which may indicate inhibition of the prime representation. Trials where the participant reported the primed syllable showed more negative eventrelated potentials at target presentation, which may indicate cognitive conflict and effortful response selection. In context of current theories, the data suggest that the interplay of a proactive inhibition bias and a reactive potential for conflict is involved in causing sequential effects on selective attention mechanisms.

Background: Situation awareness (SA) is considered to be crucial for work in safety critical orga... more Background: Situation awareness (SA) is considered to be crucial for work in safety critical organisations, yet its precise definition and an agreed upon measurement approach have yet to emerge. SA is often measured as an operator’s overview of some specific parameters within a given work setting and a given time frame, an approach that entails both advantages and disadvantages. The current approach examines whether some aspects of SA relating to workplace safety can also be captured in a context-general inventory.
Material and methods: 166 offshore maritime personnel answered the SA inventory with 13 items describing the respondent’s typical cognitions concerning safety issues.
Results: Confirmatory factor analysis of response patterns showed that the internal pattern among the items reflected the three level structure predicted by the leading theoretical model. Strengths and weaknesses of the inventory itself, as well as the approach in general are discussed, and future research directions are outlined.
Conclusions: It appears feasible to measure aspects of SA in a context-general inventory, though additional adjustment and validation is required.

Nordic Journal of Psychiatry

Introduction: Depression is associated with cognitive deficits, social withdrawal and high risk o... more Introduction: Depression is associated with cognitive deficits, social withdrawal and high risk of relapse. Several factors have been proposed as pertaining to increasing the risk of relapse, including a bias in emotional information processing. This study was carried out to examine the relationships between major depressive disorder (MDD), level of depressive symptoms and bias in emotional effortful information processing. Method: Nineteen patients diagnosed with recurrent MDD and 19 matched controls were tested with an experimental visual face-in-the-crowd paradigm including sad, happy and neutral information. The patients were tested on average 9 months after hospitalization. At testing, the patient group showed an overall decrease in depression severity symptom load as measured on the Hamilton Depression Rating Scale (HDRS), but with variable symptom load. Results: Reaction time (RT) did not vary between patients and controls in the visual face-in-the-crowd task or on a measure of psychomotor speed. In the patient group, symptom load was related to longer RTs when negative targets were shown against positive distractors. The results revealed a specific bias in response to negative emotional information. Conclusions: Symptom load in the patient group is related to a negative bias in emotional information processing that cannot be explained by psychomotor retardation.

Proceedings of the Human Factors and Ergonomics Society Annual Meeting

Five second line emergency handling teams within hydrocarbon energy industry were studied while t... more Five second line emergency handling teams within hydrocarbon energy industry were studied while they performed a scripted training scenario. To have the same knowledge as the team leader was used as an objective index of situation awareness (SA). Self-assessment of performance proved a poor indicator of objective SA. Objective SA varied according to team membership, but not according to roles in the team. Heart rate variability correlated with some objective SA measures, but not with self-report measures of SA.

Competing models of attention make different predictions of how priming from recent stimulus proc... more Competing models of attention make different predictions of how priming from recent stimulus processing could interact with intended selection. The present experiment examined the interaction between exogenous attention and endogenous priming across trial sequences. A sound cue directed attention to left, right or both sides before a dichotic syllable pair was presented. Participants were asked to report one syllable from each trial. On some trials, one of the syllables was repeated from the previous trial. Results showed that these trials had slower responses. Within these trials, the repeated syllable was selected less frequently, and the responses doing so were slower. Examined according to response choice on the preceding trial, syllables that had been ignored on the preceding trial tended to be ignored on the current trial (negative priming), while syllables that had been selected on the preceding trial tended to be selected (positive priming). Responses that followed these selection biases were faster than responses that did not. Response selection was also influenced by the attention direction cue for the current trial, but not by the cue presented on the preceding trial. The results support an attentional model where traces from the preceding processing are retained, and current selection is biased to minimize cognitive conflict between recent and current processing. Negative priming appears to be due to after-effects of preceding processing, independently of the intentions behind that processing. The study accounts for positive and negative priming of dichotic listening sequences within an established, computationally viable biased competition framework.

Brain and Cognition

It has previously been shown that task performance and frontal cortical activation increase after... more It has previously been shown that task performance and frontal cortical activation increase after cognitive conflict. This has been argued to support a model of attention where the level of conflict automatically adjusts the amount of cognitive control applied. Conceivably, conflict could also modulate lowerlevel processing pathways, which would be evident as trial-to-trial changes in domain specific activation. The present fMRI experiment used a syllable identification task where conflict is manipulated by presenting recently ignored syllables. Results showed that on trials following a high conflict trial, activation increased primarily in the planum temporale region of the left temporal cortex, an area believed to be involved in syllable discrimination. The experiment thus showed a transient, domain specific attention effect that was modulated on a trial-to-trial basis. We argue that this indicates a self-regulating system where increased levels of conflict directs resources in order to improve performance.

Laterality: Asymmetries of Body, Brain and Cognition

The dichotic listening task is typically administered by presenting a consonant–vowel (CV) syllab... more The dichotic listening task is typically administered by presenting a consonant–vowel (CV) syllable to each ear and asking the participant to report the syllable heard most clearly. The results tend to show more reports of the right ear syllable than of the left ear syllable, an effect called the right ear advantage (REA). The REA is assumed to be due to the crossing over of auditory fibres and the processing of language stimuli being lateralised to left temporal areas. However, the tendency for most dichotic listening experiments to use only CV syllable stimuli limits the extent to which the conclusions can be generalised to also apply to other speech phonemes. The current study re-examines the REA in dichotic listening by using both CV and vowel–consonant (VC) syllables and combinations thereof. Results showed a replication of the REA response pattern for both CV and VC syllables, thus indicating that the general assumption of left-side localisation of processing can be applied for both types of stimuli. Further, on trials where a CV is presented in one ear and a VC is presented in the other ear, the CV is selected more often than the VC, indicating that these phonemes have an acoustic or processing advantage.

The potential impact of implicit learning on education has been repeatedly stressed, though littl... more The potential impact of implicit learning on education has been repeatedly stressed, though little research has examined this connection directly. The current paper describes two experiments that, inspired by artificial grammar learning experiments, examine the utility of implicit learning as a method for teaching atomic bonding rules to 11e12 year old school children. Two groups were given tasks that led to explicit rule learning; two other groups were given tasks that did not lead to rule learning; and a control group was trained on irrelevant stimuli. We observed an implicit learning effect, but learning was much more effective when more explicit ways of teaching were employed. These findings suggest that mere exposure to regular material is not sufficient for effective learning of rules, and that an explicit approach to instruction is advisable.

The typical finding in dichotic listening with verbal stimuli is the right ear advantage (REA), i... more The typical finding in dichotic listening with verbal stimuli is the right ear advantage (REA), indicating a left hemisphere processing superiority, thus making this an effective tool in studying hemispheric asymmetry. It has been shown that the amplitude of the REA can be modulated by instructions to direct attention to left or right side. The current study attempted to modulate the REA by changing the dichotic listening stimulus situation. In Experiment 1, a consonant vowel (CV) syllable prime was presented binaurally briefly before the dichotic stimuli (consisting of two CVs). The prime could be the same as either the left or right ear dichotic stimulus, or it could be a different stimulus. Participants were instructed to report the CV they heard best from the dichotic syllable pair. The traditional REA was found when the prime was different from both dichotic stimuli. When the prime matched the CV in the left half of the subsequent dichotic pair, the REA was increased, while if the prime matched the right half, the REA was reduced. In order to see at which perceptual stage the modulation takes place, in Experiment 2 the prime was visual, presented on a PC screen. The same effect was seen, although the modulation of the REA was weaker. We propose that the memory trace of the prime is a source of interference, and causes cognitive control of attention to inhibit recognition of stimuli similar to recent distractors. Based on previous studies we propose that this inhibition of attention is performed by prefrontal cortical areas. Similarities to the mechanisms involved in negative priming and implications for auditory laterality studies are pointed out.

Dichotic listening to verbal stimuli results in a right ear advantage (REA), indicating a left he... more Dichotic listening to verbal stimuli results in a right ear advantage (REA), indicating a left hemisphere processing superiority. The magnitude of the REA can be modulated by instructions to direct attention to the left or right ear stimulus. A previous study from our laboratory showed that presenting a prime syllable before the presentation of the dichotic syllables increases reports of the nonprimed syllable, apparently a negative priming effect that inhibits attention to the distracting prime representation. The present study combined attention instruction and priming, making up a 3 x 3 factorial design. The prime stimulus was a single consonant–vowel syllable presented binaurally just before onset of the dichotic consonant–vowel syllables. Results showed that both instructions and priming manipulations had an effect on which dichotic stimulus was selected. There was also a significant interaction between attention instruction and priming manipulation, indicating that the mechanism for instructed attention and the mechanism for negative priming work on the same level of processing.

In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable ... more In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable pair, with instructions to ignore the prime and report one syllable from the dichotic pair. When the prime matched one of the syllables in the dichotic pair, response selection was biased towards selecting the unprimed target. The suggested mechanism was that the prime was inhibited to reduce conflict between task-irrelevant prime processing and task-relevant dichotic target processing, and a residual effect of the prime inhibition biased the resolution of the conflict between the two targets. The current experiment repeated the primed dichotic listening task in an event-related fMRI setting. The fMRI data showed that when the task-irrelevant prime matched the task-relevant targets, activations in posterior medial frontal cortex (pMFC) and in right inferior frontal gyrus (IFG) increased, which was considered to represent conflict and inhibition, respectively. Further, matching trials where the unprimed target was selected showed activation in right IFG, while matching trials where the primed target was selected showed activations in pMFC and left IFG, indicating the difference between inhibition-biased selection and unbiased selection.

The processing of a stimulus can be facilitated (positive priming) or impeded (negative priming),... more The processing of a stimulus can be facilitated (positive priming) or impeded (negative priming), depending on whether a repeated stimulus has recently been attended or ignored. The current experiment presented consecutive dichotic syllable pairs with instructions to report any syllable from each pair. The results showed that trials which repeated a syllable from the previous trial had increased response times, and the repeated syllable had a decreased likelihood of being selected. This indicates that inhibition is involved when selecting between stimuli, and that the inhibition associated with stimuli has a residual effect on subsequent selection. Closer examination showed that a repeated syllable was more likely to be ignored if the syllable had been ignored rather than attended on the previous presentation, and trials showing this response pattern had faster response times than trials that did not, thus representing an effect similar to negative priming. We suggest that a biased competition network model, in which pathways are made stronger or weaker as a residual effect of selection, can be applied to account for the observed effect. The model has support from other experimental tasks, and in contrast to prominent accounts of negative priming, it focuses on the processing performed by the network rather than on pre-onset selection criteria for processing.

Most previous studies of updating processes have not been able to contrast processes of substitut... more Most previous studies of updating processes have not been able to contrast processes of substituting items in memory with other concurrent processes. In the present investigation, we used a new task called ‘‘number updating’’ and an fMRI protocol to contrast the activation of trials that require item substitution (adding a new item to the working memory representation and suppressing an old item) with trials that involve no substitution (discarding the new item). Trials that require item substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, areas typically seen activated for working memory tasks in general. Trials that do not require substitution activated the anterior medial frontal cortex. Studies examining executive functions have associated this area with cognitive conflict, and may represent suppression of the substitution processes.

The dichotic listening experimental paradigm creates an ambiguous situation for the participant b... more The dichotic listening experimental paradigm creates an ambiguous situation for the participant by presenting two auditory stimuli simultaneously, one in each ear. Which of the stimuli the participant reports has previously been shown to depend on language lateralization and attention instructions. The current work presents three studies that introduce a novel way of manipulating which stimulus is reported in dichotic listening. The first report showed that priming one of the stimuli in the dichotic situation biases response selection away from the primed dichotic stimulus, and that the manipulation is effective with both auditory and visual priming. The second report showed that the priming manipulation can be combined with the more traditional attention instructions manipulation, and that the two types of experimental manipulation showed an interaction. The third report used fMRI to show that the task evokes activation in posterior medial frontal and right ventrolateral brain areas, and presented a theoretical model in which the activations reflect detection of cognitive conflict and inhibition, respectively. The present thesis thus shows that priming in the dichotic listening experimental paradigm modulates cognitive mechanisms, which has effects on response selection. The experimental task may prove useful as an easily administered test of inhibition in the auditory domain, with implications for examining attention functions in healthy and clinical groups.

Scandinavian Journal of Psychology, Jan 1, 2010

The classic McGurk study showed that presentation of one syllable in the visual modality simultan... more The classic McGurk study showed that presentation of one syllable in the visual modality simultaneous with a different syllable in the auditory modality creates the perception of a third, not presented syllable. The current study presented dichotic syllable pairs (one in each ear) simultaneously with video clips of a mouth pronouncing the syllables from one of the ears, or pronouncing a syllable that was not part of the dichotic pair. When asked to report the auditory stimuli, responses were shifted towards selecting the auditory stimulus from the side that matched the visual stimulus.

International …, Jan 1, 2010

Pictorial stimuli were presented in a Stroop task paradigm that enabled the recording of attentio... more Pictorial stimuli were presented in a Stroop task paradigm that enabled the recording of attentional bias. The sample comprised 33 pathological slot machine gamblers (PG) and 22 control participants. The design of the study had one between-subjects factor – Group (PGs vs control), and two within-subject factors: (1) Stimulus meaning (win-related gambling stimuli vs neutral stimuli) and (2) Exposure (subliminal vs supraliminal). The results supported the notion that the PG group had an attentional bias towards visual win-related gambling stimuli compared with the control group. Furthermore, the degree of attentional bias among the PG group was moderately negatively correlated with net loss in the week before testing. One possible treatment implication of the findings is to include in-vivo exposure sessions as a supplement to cognitive behavioural therapy for gambling. Future studies could also include non-win gambling-related stimuli and should also comprise non-pathological regular gamblers as an additional control group.

PLoS ONE, 2014

The use of nicotine in the form of &a... more The use of nicotine in the form of "snus" is substantial and increasing in some geographic areas, in particular among young people. It has previously been suggested that addictions may operate through a mechanism of attentional bias, in which stimuli representative of the dependent substance increase in salience, thus increasing the addictive behavior. However, this hypothesis has not been tested for the case of snus. The current experiment used a modified Stroop task and a dot-probe task to investigate whether 40 snus users show an attentional bias towards snus-relevant stimuli, compared to 40 non-snus users. There were no significant differences between the two groups on reaction times or accuracy on either Stroop or dot-probe task, thus failing to show an attentional bias towards snus-relevant stimuli for snus users. This could imply that other mechanisms may contribute to maintenance of snus use than for other addictions. However, this is the first experimental study investigating attentional bias in snus users, and more research is warranted.

Journal of Cognitive Engineering and Decision Making, 2013

The aim of this paper is to present a methodology where the extent of information sharing among t... more The aim of this paper is to present a methodology where the extent of information sharing among team members is used as an indicator of shared mental models (SMM) and situation awareness (SA). Data collection procedures and probe materials are described for two field experiments performed among emergency management teams in the hydrocarbon industry. Methods are suggested for calculating a “similarity index” by comparing a team member’s responses with the average response in the team or with the responses of the team member assumed to be best informed. It is argued that similarity to team average could be a measure of SMM, whereas similarity to the best-informed team member could be argued to be an indicator of SA. The degree of compliance in responding to the probes is reported, as is the degree to which the extent of shared information differed between the probe questions or according to team positions. Lessons learned from the data collection are summarized, and the applicability of the similarity index as a measure of SA is discussed. Some advantages of the current approach are presented, as are challenges and inherent assumptions in future applications of this approach.

Brain and Cognition, 2013

Sequences of events can affect selective attention either through proactive mechanisms, through r... more Sequences of events can affect selective attention either through proactive mechanisms, through reactive mechanisms, or through a combination of the two. The current study examined electrophysiological responses to both prime and target stimuli in a primed dichotic listening task. Each trial presented a distractor prime syllable followed by two simultaneous syllables, and participants were asked to report one of the simultaneous syllables. Trials where the participant reported the non-primed syllable showed more negative event-related potentials at prime presentation, which may indicate inhibition of the prime representation. Trials where the participant reported the primed syllable showed more negative eventrelated potentials at target presentation, which may indicate cognitive conflict and effortful response selection. In context of current theories, the data suggest that the interplay of a proactive inhibition bias and a reactive potential for conflict is involved in causing sequential effects on selective attention mechanisms.

Background: Situation awareness (SA) is considered to be crucial for work in safety critical orga... more Background: Situation awareness (SA) is considered to be crucial for work in safety critical organisations, yet its precise definition and an agreed upon measurement approach have yet to emerge. SA is often measured as an operator’s overview of some specific parameters within a given work setting and a given time frame, an approach that entails both advantages and disadvantages. The current approach examines whether some aspects of SA relating to workplace safety can also be captured in a context-general inventory.
Material and methods: 166 offshore maritime personnel answered the SA inventory with 13 items describing the respondent’s typical cognitions concerning safety issues.
Results: Confirmatory factor analysis of response patterns showed that the internal pattern among the items reflected the three level structure predicted by the leading theoretical model. Strengths and weaknesses of the inventory itself, as well as the approach in general are discussed, and future research directions are outlined.
Conclusions: It appears feasible to measure aspects of SA in a context-general inventory, though additional adjustment and validation is required.

Nordic Journal of Psychiatry

Introduction: Depression is associated with cognitive deficits, social withdrawal and high risk o... more Introduction: Depression is associated with cognitive deficits, social withdrawal and high risk of relapse. Several factors have been proposed as pertaining to increasing the risk of relapse, including a bias in emotional information processing. This study was carried out to examine the relationships between major depressive disorder (MDD), level of depressive symptoms and bias in emotional effortful information processing. Method: Nineteen patients diagnosed with recurrent MDD and 19 matched controls were tested with an experimental visual face-in-the-crowd paradigm including sad, happy and neutral information. The patients were tested on average 9 months after hospitalization. At testing, the patient group showed an overall decrease in depression severity symptom load as measured on the Hamilton Depression Rating Scale (HDRS), but with variable symptom load. Results: Reaction time (RT) did not vary between patients and controls in the visual face-in-the-crowd task or on a measure of psychomotor speed. In the patient group, symptom load was related to longer RTs when negative targets were shown against positive distractors. The results revealed a specific bias in response to negative emotional information. Conclusions: Symptom load in the patient group is related to a negative bias in emotional information processing that cannot be explained by psychomotor retardation.

Proceedings of the Human Factors and Ergonomics Society Annual Meeting

Five second line emergency handling teams within hydrocarbon energy industry were studied while t... more Five second line emergency handling teams within hydrocarbon energy industry were studied while they performed a scripted training scenario. To have the same knowledge as the team leader was used as an objective index of situation awareness (SA). Self-assessment of performance proved a poor indicator of objective SA. Objective SA varied according to team membership, but not according to roles in the team. Heart rate variability correlated with some objective SA measures, but not with self-report measures of SA.

Competing models of attention make different predictions of how priming from recent stimulus proc... more Competing models of attention make different predictions of how priming from recent stimulus processing could interact with intended selection. The present experiment examined the interaction between exogenous attention and endogenous priming across trial sequences. A sound cue directed attention to left, right or both sides before a dichotic syllable pair was presented. Participants were asked to report one syllable from each trial. On some trials, one of the syllables was repeated from the previous trial. Results showed that these trials had slower responses. Within these trials, the repeated syllable was selected less frequently, and the responses doing so were slower. Examined according to response choice on the preceding trial, syllables that had been ignored on the preceding trial tended to be ignored on the current trial (negative priming), while syllables that had been selected on the preceding trial tended to be selected (positive priming). Responses that followed these selection biases were faster than responses that did not. Response selection was also influenced by the attention direction cue for the current trial, but not by the cue presented on the preceding trial. The results support an attentional model where traces from the preceding processing are retained, and current selection is biased to minimize cognitive conflict between recent and current processing. Negative priming appears to be due to after-effects of preceding processing, independently of the intentions behind that processing. The study accounts for positive and negative priming of dichotic listening sequences within an established, computationally viable biased competition framework.

Brain and Cognition

It has previously been shown that task performance and frontal cortical activation increase after... more It has previously been shown that task performance and frontal cortical activation increase after cognitive conflict. This has been argued to support a model of attention where the level of conflict automatically adjusts the amount of cognitive control applied. Conceivably, conflict could also modulate lowerlevel processing pathways, which would be evident as trial-to-trial changes in domain specific activation. The present fMRI experiment used a syllable identification task where conflict is manipulated by presenting recently ignored syllables. Results showed that on trials following a high conflict trial, activation increased primarily in the planum temporale region of the left temporal cortex, an area believed to be involved in syllable discrimination. The experiment thus showed a transient, domain specific attention effect that was modulated on a trial-to-trial basis. We argue that this indicates a self-regulating system where increased levels of conflict directs resources in order to improve performance.

Laterality: Asymmetries of Body, Brain and Cognition

The dichotic listening task is typically administered by presenting a consonant–vowel (CV) syllab... more The dichotic listening task is typically administered by presenting a consonant–vowel (CV) syllable to each ear and asking the participant to report the syllable heard most clearly. The results tend to show more reports of the right ear syllable than of the left ear syllable, an effect called the right ear advantage (REA). The REA is assumed to be due to the crossing over of auditory fibres and the processing of language stimuli being lateralised to left temporal areas. However, the tendency for most dichotic listening experiments to use only CV syllable stimuli limits the extent to which the conclusions can be generalised to also apply to other speech phonemes. The current study re-examines the REA in dichotic listening by using both CV and vowel–consonant (VC) syllables and combinations thereof. Results showed a replication of the REA response pattern for both CV and VC syllables, thus indicating that the general assumption of left-side localisation of processing can be applied for both types of stimuli. Further, on trials where a CV is presented in one ear and a VC is presented in the other ear, the CV is selected more often than the VC, indicating that these phonemes have an acoustic or processing advantage.

The potential impact of implicit learning on education has been repeatedly stressed, though littl... more The potential impact of implicit learning on education has been repeatedly stressed, though little research has examined this connection directly. The current paper describes two experiments that, inspired by artificial grammar learning experiments, examine the utility of implicit learning as a method for teaching atomic bonding rules to 11e12 year old school children. Two groups were given tasks that led to explicit rule learning; two other groups were given tasks that did not lead to rule learning; and a control group was trained on irrelevant stimuli. We observed an implicit learning effect, but learning was much more effective when more explicit ways of teaching were employed. These findings suggest that mere exposure to regular material is not sufficient for effective learning of rules, and that an explicit approach to instruction is advisable.

The typical finding in dichotic listening with verbal stimuli is the right ear advantage (REA), i... more The typical finding in dichotic listening with verbal stimuli is the right ear advantage (REA), indicating a left hemisphere processing superiority, thus making this an effective tool in studying hemispheric asymmetry. It has been shown that the amplitude of the REA can be modulated by instructions to direct attention to left or right side. The current study attempted to modulate the REA by changing the dichotic listening stimulus situation. In Experiment 1, a consonant vowel (CV) syllable prime was presented binaurally briefly before the dichotic stimuli (consisting of two CVs). The prime could be the same as either the left or right ear dichotic stimulus, or it could be a different stimulus. Participants were instructed to report the CV they heard best from the dichotic syllable pair. The traditional REA was found when the prime was different from both dichotic stimuli. When the prime matched the CV in the left half of the subsequent dichotic pair, the REA was increased, while if the prime matched the right half, the REA was reduced. In order to see at which perceptual stage the modulation takes place, in Experiment 2 the prime was visual, presented on a PC screen. The same effect was seen, although the modulation of the REA was weaker. We propose that the memory trace of the prime is a source of interference, and causes cognitive control of attention to inhibit recognition of stimuli similar to recent distractors. Based on previous studies we propose that this inhibition of attention is performed by prefrontal cortical areas. Similarities to the mechanisms involved in negative priming and implications for auditory laterality studies are pointed out.

Dichotic listening to verbal stimuli results in a right ear advantage (REA), indicating a left he... more Dichotic listening to verbal stimuli results in a right ear advantage (REA), indicating a left hemisphere processing superiority. The magnitude of the REA can be modulated by instructions to direct attention to the left or right ear stimulus. A previous study from our laboratory showed that presenting a prime syllable before the presentation of the dichotic syllables increases reports of the nonprimed syllable, apparently a negative priming effect that inhibits attention to the distracting prime representation. The present study combined attention instruction and priming, making up a 3 x 3 factorial design. The prime stimulus was a single consonant–vowel syllable presented binaurally just before onset of the dichotic consonant–vowel syllables. Results showed that both instructions and priming manipulations had an effect on which dichotic stimulus was selected. There was also a significant interaction between attention instruction and priming manipulation, indicating that the mechanism for instructed attention and the mechanism for negative priming work on the same level of processing.

In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable ... more In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable pair, with instructions to ignore the prime and report one syllable from the dichotic pair. When the prime matched one of the syllables in the dichotic pair, response selection was biased towards selecting the unprimed target. The suggested mechanism was that the prime was inhibited to reduce conflict between task-irrelevant prime processing and task-relevant dichotic target processing, and a residual effect of the prime inhibition biased the resolution of the conflict between the two targets. The current experiment repeated the primed dichotic listening task in an event-related fMRI setting. The fMRI data showed that when the task-irrelevant prime matched the task-relevant targets, activations in posterior medial frontal cortex (pMFC) and in right inferior frontal gyrus (IFG) increased, which was considered to represent conflict and inhibition, respectively. Further, matching trials where the unprimed target was selected showed activation in right IFG, while matching trials where the primed target was selected showed activations in pMFC and left IFG, indicating the difference between inhibition-biased selection and unbiased selection.

The processing of a stimulus can be facilitated (positive priming) or impeded (negative priming),... more The processing of a stimulus can be facilitated (positive priming) or impeded (negative priming), depending on whether a repeated stimulus has recently been attended or ignored. The current experiment presented consecutive dichotic syllable pairs with instructions to report any syllable from each pair. The results showed that trials which repeated a syllable from the previous trial had increased response times, and the repeated syllable had a decreased likelihood of being selected. This indicates that inhibition is involved when selecting between stimuli, and that the inhibition associated with stimuli has a residual effect on subsequent selection. Closer examination showed that a repeated syllable was more likely to be ignored if the syllable had been ignored rather than attended on the previous presentation, and trials showing this response pattern had faster response times than trials that did not, thus representing an effect similar to negative priming. We suggest that a biased competition network model, in which pathways are made stronger or weaker as a residual effect of selection, can be applied to account for the observed effect. The model has support from other experimental tasks, and in contrast to prominent accounts of negative priming, it focuses on the processing performed by the network rather than on pre-onset selection criteria for processing.

Most previous studies of updating processes have not been able to contrast processes of substitut... more Most previous studies of updating processes have not been able to contrast processes of substituting items in memory with other concurrent processes. In the present investigation, we used a new task called ‘‘number updating’’ and an fMRI protocol to contrast the activation of trials that require item substitution (adding a new item to the working memory representation and suppressing an old item) with trials that involve no substitution (discarding the new item). Trials that require item substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, areas typically seen activated for working memory tasks in general. Trials that do not require substitution activated the anterior medial frontal cortex. Studies examining executive functions have associated this area with cognitive conflict, and may represent suppression of the substitution processes.

The dichotic listening experimental paradigm creates an ambiguous situation for the participant b... more The dichotic listening experimental paradigm creates an ambiguous situation for the participant by presenting two auditory stimuli simultaneously, one in each ear. Which of the stimuli the participant reports has previously been shown to depend on language lateralization and attention instructions. The current work presents three studies that introduce a novel way of manipulating which stimulus is reported in dichotic listening. The first report showed that priming one of the stimuli in the dichotic situation biases response selection away from the primed dichotic stimulus, and that the manipulation is effective with both auditory and visual priming. The second report showed that the priming manipulation can be combined with the more traditional attention instructions manipulation, and that the two types of experimental manipulation showed an interaction. The third report used fMRI to show that the task evokes activation in posterior medial frontal and right ventrolateral brain areas, and presented a theoretical model in which the activations reflect detection of cognitive conflict and inhibition, respectively. The present thesis thus shows that priming in the dichotic listening experimental paradigm modulates cognitive mechanisms, which has effects on response selection. The experimental task may prove useful as an easily administered test of inhibition in the auditory domain, with implications for examining attention functions in healthy and clinical groups.

Scandinavian Journal of Psychology, Jan 1, 2010

The classic McGurk study showed that presentation of one syllable in the visual modality simultan... more The classic McGurk study showed that presentation of one syllable in the visual modality simultaneous with a different syllable in the auditory modality creates the perception of a third, not presented syllable. The current study presented dichotic syllable pairs (one in each ear) simultaneously with video clips of a mouth pronouncing the syllables from one of the ears, or pronouncing a syllable that was not part of the dichotic pair. When asked to report the auditory stimuli, responses were shifted towards selecting the auditory stimulus from the side that matched the visual stimulus.

International …, Jan 1, 2010

Pictorial stimuli were presented in a Stroop task paradigm that enabled the recording of attentio... more Pictorial stimuli were presented in a Stroop task paradigm that enabled the recording of attentional bias. The sample comprised 33 pathological slot machine gamblers (PG) and 22 control participants. The design of the study had one between-subjects factor – Group (PGs vs control), and two within-subject factors: (1) Stimulus meaning (win-related gambling stimuli vs neutral stimuli) and (2) Exposure (subliminal vs supraliminal). The results supported the notion that the PG group had an attentional bias towards visual win-related gambling stimuli compared with the control group. Furthermore, the degree of attentional bias among the PG group was moderately negatively correlated with net loss in the week before testing. One possible treatment implication of the findings is to include in-vivo exposure sessions as a supplement to cognitive behavioural therapy for gambling. Future studies could also include non-win gambling-related stimuli and should also comprise non-pathological regular gamblers as an additional control group.