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Sökning: FÖRF:(Mats Dahl)

  • Resultat 11-16 av 16
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11.
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12.
  • Dahl, Mats, et al. (författare)
  • The effect of emotional valance on recollective experience and confidence judgments
  • 2003
  • Ingår i: Psychology & Law International Interdisciplinary Conference 2003,2003-07-07 - 2003-07-12. ; , s. 110-110
  • Konferensbidrag (refereegranskat)abstract
    • The study investigated the effect of positive and negative emotional valence (I.A.P.S pictures) on recollective experience, using the remember-know paradigm (Tulving, 1985), and confidence judgements. The negative valenced pictures were hypothesised elicit the recollective experience to a larger extent and to entail a higher degree of confidence in the correctness of memory responses than positive valenced pictures. In the acquisition phase of all three experiments four pictures were presented simultaneously, one valenced picture (either positive or negative) and three neutral pictures. Next, in the test phase a recognition test of the valenced pictures followed. Depending on the experiment, the participants made new/old responses and either remember/know judgements of old responses or confidence judgements of the correctness of their new/old responses. The results of Experiment 1 and 2 showed that, compared with ”know” responses, the frequency of ”remember” responses was significantly higher for negative than for positive pictures. No differences in recognition memory performance were found between negative and positive pictures. The results of Experiment 3 showed that negative pictures was associated with slightly higher accuracy and significantly higher confidence judgements than positive pictures, and that realism in confidence judgements did not differ between the valence types. These results suggest that the emotional valence of witnessed events affect the phenomenological quality and degree of confidence of memorial testimony.
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13.
  • Dahl, Mats (författare)
  • Processing Asymmetries of Emotionally Valenced Stimuli
  • 2002
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The central phenomenon investigated concerns the valence-based process asymmetry found in several earlier studies (e.g. Pratto & John, 1991; Taylor, 1991), where negative stimuli seem to initiate more thorough processing than positive stimuli. This finding was consistent in the three empirical studies forming this dissertation. In Study 1 (three experiments) emotionally valenced words were presented at the centre of pictures of emotional faces (angry, sad, disgusted, happy). The results showed a general positive valence advantage (PVA) in reaction times for positive words relative to negative words. Furthermore, except for the words imposed on pictures of angry faces in the first experiment, the PVA increased when words were imposed on pictures of happy faces. In Study 2, the priming effects of emotional words were tested. In both experiments, two conditions were used. When valence had been activated by a valence categorisation task, negatively primed words resulted in prolonged RTs in a subsequent word recognition test. In the other condition, where the participants just read the word, no valence dependent latency differences were found. The results provide support for a non-automatic appraisal of the valence when using words as stimuli.In Study 3 (three experiments) neutral words were imposed on emotional pictures (negative, neutral and positive) in the encoding phase. In the following test phase the phenomenological quality of the memory was measured using the Remember-Know paradigm (Tulving, 1985). The results showed a decrease in the frequency of “remember” responses, suggesting less episodic detail in the retention experience of the to-be-remembered item, when the words had been presented on negative pictures relative to positive pictures. The third experiment tested whether the neutral words were primed by the valence of the encoding context (picture) and whether such affective information could be used as a cue in a subsequent source monitoring task (Johnson, Hashtroudi, Lindsay, 1993). However, no support for the valence-as-a-cue hypothesis was found. The results of the three studies are discussed within the framework of appraisal theories (Lazarus, 1991; Scherer, 2001) and Taylor’s mobilization-minimization hypothesis, and an evolutionary explanation for the processing asymmetry is considered.
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14.
  • Stenberg, Georg, 1947-, et al. (författare)
  • Judging words at face value : interference in a word processing task reveals automatic processing of affective facial expressions
  • 1998
  • Ingår i: Cognition & Emotion. - 0269-9931 .- 1464-0600. ; 12:6, s. 755-782
  • Tidskriftsartikel (refereegranskat)abstract
    • Earlier research has indicated that some characteristics of facial expressions may be automatically processed. This study investigated automaticity as evidenced by involuntary interference in a word evaluation task. Compound stimuli, consisting of words superimposed on pictures of affective faces, were presented to subjects who were given the task of evaluating the affective valence of the words while disregarding the faces. Results of three experiments showed that word evaluation was influenced by the concurrently shown affective faces. Overall, negative words were found to require longer latencies, indicating that more processing resources are invested in negative than in positive stimuli. This speed advantage for positive words was modified by the faces. Negative words were facilitated, relative to positive ones, when shown with a negative expression, e.g. a sad face. Correspondingly, negative words were inhibited, relative to positive ones, when shown with a positive expression, e.g. a happy face. The results are consistent with automatic, involuntary semantic processing of affective facial expressions.
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15.
  • Dahl, Mats, et al. (författare)
  • Analysis of eyewitness testimony in a police shooting with fatal outcome–Manifestations of spatial and temporal distortions
  • Ingår i: Cogent Psychology. - : Cogent OA. - 2331-1908. ; 5:1, s. 1-10
  • Tidskriftsartikel (refereegranskat)abstract
    • Eyewitness statements are commonly used in the criminal justice system and viewed as having a high-probative value, especially when the witness has no motive to lie, other witness recollection corroborates the account, or the witness is highly confident. A fatal police shooting incident in Sweden had 13 witnesses (nine civilians and four police officers) and was also filmed with two mobile phones. All interviews were conducted before witnesses viewed the films, allowing for the analysis of discrepancies between their statements and the videos. In this incident, a police patrol was sent to find out a man who was reported to have attacked two persons with a knife. When found, the perpetrator refused to obey the officer’s commands, and the police eventually shot at him. The analysis showed clear differences between the witness testimonies and the film. Elements associated with perceived threat, for example, the assailant’s armament and movement direction and number of shots fired, were remembered fairly accurately. However, most witnesses poorly recollected when, that is, after which shot, the assailant fell to the ground. Moreover, memory of the actual order of events was altered and important aspects omitted that were crucial from a legal point of view.
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16.
  • Sikström, Sverker, et al. (författare)
  • The Role of Sparsely Distributed Representations in Familiarity Recognition of Verbal and Olfactory Materials
  • Ingår i: Cognitive Processing. - : Springer. - 1612-4782 .- 1612-4790. ; 19:4, s. 481-494
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the generalized signal detection theory (GSDT), where familiarity is described by a sparse binomial distribution of binary node activity rather than by normal distribution of familiarity. Items are presented in a distributed representation, where each node receives either noise only, or signal and noise. An old response (i.e., a ‘yes’ response) is made if at least one node receives signal plus noise that is larger than the activation threshold, and item variability is determined by the distribution of activated nodes as the threshold is varied. A distinct representation leads to better performance and a lower ratio of new to old item variability, than a more distributed and less distinct representations. Here we apply the GSDT to empirical data on verbal and olfactory memory and suggest that verbal memory relies on a distinct neural item representation whereas olfactory memory has a fuzzy neural representation leading to poorer memory and inducing a larger ratio of new to old item variability.
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