- Email: [email protected]
Is there an affective working memory deficit in patients with chronic schizophrenia?
Schizophrenia Research 138 (2012) 99–101
Contents lists available at SciVerse ScienceDirect
Schizophrenia Research journal homepage: www.elsevier.com/locate/schres
Is there an affective working memory deficit in patients with chronic schizophrenia? Nicola Mammarella a,⁎, Beth Fairfield a, Valeria De Leonardis a, Barbara Carretti b, Erika Borella b, Elisa Frisullo a, Alberto Di Domenico a a b
Department of Neuroscience and Imaging, University of Chieti, Italy Department of General Psychology, University of Padua, Italy
a r t i c l e
i n f o
Article history: Received 23 June 2011 Received in revised form 7 March 2012 Accepted 21 March 2012 Available online 15 April 2012 Keywords: Working memory Emotion Schizophrenia
a b s t r a c t Research interest in affective working memory has rapidly grown in the last decade. In this study we investigated working memory functions for affective and neutral words in a group of 22 patients with chronic schizophrenia and 22 healthy controls. In particular, participants were administered the operation working memory span task in which affective and neutral words had to be remembered. Results showed that patients made significantly more intrusion errors, recalling off-goal information, and showed poorer long-term memory performance than controls. In addition, affective trials showed the largest number of intrusion errors. These results suggest that a general attentional control deficit, especially over affective information, may underly failures to remember in chronic schizophrenia patients. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Emotion regulation skills are fundamental for many everyday activities since all individuals typically interact with valenced environments. Schizophrenia patients show remarkable impairments in Working Memory (WM) in both verbal and visuo-spatial domains (e.g., Quee et al., 2011) as well as in the integration between the two (e.g., Burglen et al., 2004; Lee and Park, 2005). However, most of these studies used neutral valenced information. Recently, a series of studies showed that schizophrenia patients are also impaired in the short maintenance and control over affective informantion. A study by Gard et al. (2011), for instance, found that schizophrenia patients had difficulties maintaining the intensity of previously presented emotional pictures in WM and that this occurred for both positive and negative pictures, while Habel et al. (2010) showed that schizophrenia patients had difficulties controlling negative emotional information during a n-back WM task (but see Diaz et al. (2011) for a different result), where negative pictures intefered with the participants'ability to compare target stimuli with preceeding ones. Nevertheless, the available data do not help to directly investigate the effect of affective information on WM performance, and to date, as far as we know, no studies have used a classical WM span task procedure to investigate affective information processing in schizophrenia. In typical WM span tasks (e.g., Daneman and Carpenter, 1980; Engle and Kane, 2004), participants are required to process (read and judge) a series of sentences, words or operations, and remember final words/digits in their correct serial order. These tasks have been shown to entail concurrent processing and short-term
storage demands coupled with an attentional control component (that might be indexed by the number of intrusion errors) to limit interference between processing and storage. Accordingly, in this study we compared WM performance in a group of chronic schizophrenia and healthy controls using an adaptation of the classical operation WM span task (Turner and Engle, 1989), widely used in clinical settings, in which affective words were used. The interesting methodological aspect of this work was to ensure active maintenance of affective to-be-remembered stimuli in WM by making participants process a series of arithmetic operations and remember only final target words (affective and neutral ones). In line with a well-established deficit in cognitive control (e.g., Smith et al., 2011), we expect schizophrenia patients to show a greater number of intrusion errors especially for affective stimuli compared to controls. In addition, a series of studies on healthy participants (e.g., Dreisbach and Goschke, 2004; Dreisbach, 2006; Rowe et al., 2007) found that positive emotions generally broad the focus of attention during the execution of a cognitive task, leading to processing of both relevant and irrelevant information. If so, intrusion errors should be particularly pronounced with positive trials. However, no studies, to our knowledge, have investigated this effect in schizophrenia patients. Therefore our work is an exploratory study aimed at verifying whether the same pattern of intrusion errors occurs in schizophrenia. 2. Materials and method 2.1. Participants
⁎ Corresponding author at: Department of Neuroscience and Imaging, University of Chieti, Italy. Tel.: + 39 0871 355 4204; fax: + 39 0871 355 4163. E-mail address: [email protected] (N. Mammarella). 0920-9964/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2012.03.028
Demographic and clinical data are summarized in Table 1. This study included 22 patients with chronic schizophrenia spectrum disorder and
100
N. Mammarella et al. / Schizophrenia Research 138 (2012) 99–101
Table 1 Demographic and clinical characteristics of patients and controls according to mean scores and standard deviations in parentheses. Chronic
Controls
N Age (years)
22 45.7 (7.7)
22 44.1 (4.8)
Gender Female Male Education (years) Paranoid Residual Duration of illness (years) Forward digit span Backward digit span
10 12 8.4 (3.3) 13 9 22.3 (7.5) 4.2 (1.2)a 5.1 (1.3)
10 12 9.7 (4.1)
PANAS Positive Negative PANSS total Positive total Negative total
29.8 17.8 66.4 15.0 18.0
Neuroleptic medication
No. of patients
Clozapine Haloperidol Aripiprazole Olanzapine Quetiapine Chlorpromazine
5 15 7 7 8 2
(7.5)a (4.4)a (15.3) (4.22) (6.15)
7.9 (1.8)a 7.2 (1.8)
21.7 (5.9) 18.0 (6.3)
a p b .05; the forward and backward digit span are from WAIS-R (Wechsler, 1981); the PANAS (Positive and Negative Affective Scale) is from Watson et al. (1988); the PANSS (Positive and Negative Syndrome Scale) is from Kay et al. (1987).
affective word database of 200 words developed in our lab and judged by an independent group of 100 students in terms of valence and arousal on a 9-point scale. The 28 positive words had a mean valence of 7.8 (1.5) and a mean arousal level of 5.9 (2.8); the 28 negative words had a mean valence of 2.4 (1.8) and a mean arousal level of 5.9 (2.7). Finally the 28 neutral words had a mean valence of 5.5 (1.9) and a mean arousal level of 2.7 (2.3). All valenced sets were presented to participants, that is, all span levels were administered. The order of the valenced set was counterbalanced across participants. Following the WM phase, an unexpected yes–no recognition memory task was presented. For the recognition memory test, working memory words were intermixed with new words. A total of 126 words were presented (28 old negative, 28 old positive, 28 old neutral and 42 new items with comparable valence and arousal levels as the target items used in the WM span: 14 negative, 14 positive and 14 neutral). Participants were asked to respond “yes” on a prepared grid if they remembered having experienced the word or “no” if they did not. 3. Results 3.1. Data analysis Test data were analyzed using Statistica 6.0 (Statsoft). We used mean proportional numbers of correct recalled words and mean proportional numbers of intrusions errors (i.e., number of recalled words from trials within the same set) as a function of valence as dependent WM measures. The correction criterion was correspondence between seen word and recalled word, in the correct position. Therefore, if a participant made a mistake in calculating the sum of an arithmetic operation but correctly recalled the seen word at the end of the trial, it was counted as a correct response unless the number of errors was above 15% of the total operations. For the recognition memory task, accuracy scores were computed as HITs − FAs. HITs are the proportion of old stimuli correctly recognized as old, while FAs are the proportion of new stimuli recognized as old. Results are presented in Table 2. Between-subjects comparisons within the patients's group did not reveal any significant differences linked to the type of schizophrenia in any considered measures. Accordingly, we collapsed patients' data. Lastly, it must be underlined that these data should be taken with caution as the number of participants does not allow strong statistical power.
22 non-psychiatric comparison participants. Patients were recruited from a chronic psychiatric unit. Diagnoses were made according to the DSM-IV criteria, as determined by the structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) (SCID), by a board-certified attending research team of psychiatrists. Twenty-two healthy adults were matched to patients for age, education and gender. They were recruited through University advertisements. No participants had a history of traumatic brain injury, epilepsy, alcoholism or substance abuse, other diagnosable neurological conditions or organic mental disorder, nor were they being treated with antidepressants, benzodiazepines or lithium. Additionally, controls were excluded if they reported past or present psychiatric disorders, as well as if a first-degree relative had sought psychiatric diagnosis or treatment. Before the experimental task, both groups received the PANAS to evaluate their baseline subjective mood. Schizophrenia patients reported a greater number of positive compared to negative emotions (p b .05), while no differences were detected between positive and negative mood in the control group.
The effect of group was not significant F(1,42) = 1.59 p = .20 as the number of correct words was .78 in the control group and .80 in the schizophrenia patients group. The valence effect was also not significant, F b 1, as both groups recalled a comparable number of affective (positive .80, negative .79) and neutral words (.79). Finally, the two-way interaction was not significant, F b 1.
2.2. Materials and procedure
3.3. Intrusions
The operation span task requires participants to solve a series of math operations while remembering a set of unrelated words. Participants were presented with one math operation at a time, centered on a computer screen followed by a target word. They solved the math problem and read the target word aloud. The operation-word strings were presented in sets of two to five items. Following each complete set, participants were cued to recall target words in the correct order of presentation (e.g. a two item set: (2 + 5) − 2 = 5, T/F? JOY; (7 − 2) + 3 = 6, T/F? LOVE, Recall: JOY, LOVE). Four sets of 4 different lengths (from 2 to 5) were constructed for each affective valence (positive, negative and neutral). Stimuli items for the operation span task consisted in 84 arithmetic operations and 84 target words. Words were selected from an
There was a significant effect of group F(1,42) = 47.42 p b .001, η 2 = .53, as schizophrenia patients made more intrusions (.15) compared to controls (.04). The effect of valence was also significant,
3.2. Correct recall
Table 2 Mean proportional scores of correct recalled words and intrusions in the emotion operation working memory span task as a function of group and valence. Standard deviations are in parentheses. Correct recall
Patients Controls
Intrusion errors
N
Positive
Negative
Neutral
Positive
Negative
Neutral
22 22
.81 (.11) .79 (.10)
.80 (.08) .77 (.10)
.80 (.09) .77 (.09)
.15 (.08) .05 (.04)
.16 (.07) .04 (.04)
.15 (.09) .02 (.03)
N. Mammarella et al. / Schizophrenia Research 138 (2012) 99–101
F(2,84) = 3.61 p b .01, η 2 = .10 as intrusions were typically more positive than neutral (p b .05). The two-way interaction was not significant, F b 1. 3.4. Recognition There was a significant effect of group F(1,42) = 45.79 p b .001 η 2 = .52, as controls were more accurate (.61) than patients (.31). The effect of valence was also significant, F(2,84) = 4.31 p b .05, η 2 = .09: negative words (.53) were recognized better than positive (.43) and neutral words (.42). Finally, the two-way interaction was not significant, F b 1. 4. Discussion One of the goals of the present study was to further clarify affective WM performance in chronic schizophrenia since intervention that can increase emotional WM may be beneficial as training for emotion regulation abilities. We found comparable recall of final target words across both groups when we considered the number of correctly recalled words. However, our data highlighted impaired WM performance in our affective operation span task in terms of a greater number of intrusion errors confirming the well-documented general attentional control and WM impairments in schizophrenia (e.g., Smith et al., 2011). The second important goal of our study was to investigate the role of valence within this WM paradigm. Thus, valence was manipulated in order to observe how schizophrenia patients control affective words. In line with previous studies (e.g., Hall et al., 2007), our results support the role of valence in their shortterm forgetting. In fact, although both groups showed valenced intrusion errors, these were particularly marked for schizophrenia. Retention in long-term memory also showed a unique contribution of valence as participants were more accurate in recognizing negative words compared with the other types of words and this was particularly true for schizophrenia patients. These long-term memory data are consistent with the WM data as deficient inhibitory attentional control over positive words later favored recognition for negative words (Hasher et al., 2007). In part, our findings are in line with a series of studies (e.g., Dreisbach and Goschke, 2004; Dreisbach, 2006; Rowe et al., 2007) which found a greater tendency to be distracted by positive rather than negative emotions. Our additional interpretation is that the greater number of positive intrusion errors in the patients group may be also due to their tendency to maintain a positive affective state. In fact, we found that patients reported more positive than negative moods. Altogether, our overall results are in line with a general attention control deficit in chronic schizophrenia, and suggest that affective information may increase their forgetting in WM. Role of funding source No funding sources were involved in this study.
101
Contributors Authors Mammarella, Fairfield, Carretti and Borella all contributed to drafting the manuscript. Author Mammarella was both principal investigator and project director of the study. Authors Carretti and Borella designed the experimental protocol. Authors Borella and Frisullo were involved in experiment programming. Authors Di Domenico and Frisullo undertook statistical analyses. Authors De Leornardis and Fairfield were involved in data collection and data management. All authors have contributed to and have approved the final manuscript. Conflict of interest All authors declare that they have no conflicts of interest. Acknowledgements The authors are grateful to all those who participated in our research study.
References Burglen, F., Marczewski, P., Mitchell, K.J., van der Linden, M., Johnson, M.K., Danion, J.M., Salamé, P., 2004. Impaired performance in a working memory binding task in patients with schizophrenia. Psychiatry Res. 125 (3), 247–255. Daneman, M., Carpenter, P.A., 1980. Individual differences in WM and reading. J. Verbal Learn. Verbal Behav. 19 (4), 450–466. Diaz, M.T., He, G., Gadde, S., Bellion, C., Belger, A., Voyvodic, J.T., McCarthy, G., 2011. The influence of emotional distraction on verbal working memory: an fMRI investigation comparing individuals with schizophrenia and healthy adults. J. Psychiatr. Res. Mar 15. [Epub ahead of print]. Dreisbach, G., 2006. How positive affect modulates cognitive control: the costs and benefits of reduced maintenance capability. Brain Cogn. 60 (1), 11–19. Dreisbach, G., Goschke, T., 2004. How positive affect modulates cognitive control: reduced perseveration at the cost of increased distractibility. J. Exp. Psychol. Learn. Mem. Cogn. 30 (2), 343–353. Engle, R.W., Kane, M.J., 2004. Executive attention, working memory capacity, and a two-factor theory of cognitive control. In: Ross, B.H. (Ed.), The Psychology of Learning and Motivation, Vol. 44. Academic Press, New York, pp. 145–199. Gard, D.E., Cooper, S., Fisher, M., Genevsky, A., Mikels, J.A., Vinogradov, S., 2011. Evidence for an emotion maintenance deficit in schizophrenia. Psychiatry Res. 187 (1–2), 24–29. Habel, U., Pauly, K., Koch, K., Kellermann, T., Reske, M., Backes, V., Stöcker, T., Amunts, K., Shah, N.J., Schneider, F., 2010. Emotion–cognition interactions in schizophrenia. World J. Biol. Psychiatry 11 (8), 934–944. Hall, J., Harris, J.M., McKirdy, J.W., Johnstone, E.C., Lawrie, S.M., 2007. Emotional memory in schizophrenia. Neuropsychologia 45, 1152–1159. Hasher, L., Lustig, C., Zacks, R., 2007. Inhibitory mechanisms and the control of attention. In: Conway, A.R.A., Jarrold, C., Kane, M.J., Miyake, A., Towse, J.N. (Eds.), Variation in working memory. Oxford University Press, New York, pp. 227–249. Kay, S.R., Fiszbein, A., Opler, L.A., 1987. The positive and negative syndrome scale (PANSS) for schizophrenia. Schizophr. Bull. 13, 261–276. Lee, J., Park, S., 2005. Working memory impairments in schizophrenia: a meta-analysis. J. Abnorm. Psychol. 114 (4), 599–611. Quee, P.J., Eling, P.A., van der Heijden, F.M., Hildebrandt, H., 2011. Working memory in schizophrenia: a systematic study of specific modalities and processes. Psychiatry Res. 185 (1–2), 54–59. Rowe, G., Hirsh, J.B., Anderson, A.K., 2007. Positive affect increases the breadth of attentional selection. Proc. Natl. Acad. Sci. U. S. A. 104 (1), 383–388. Smith, E.E., Eich, T.S., Cebenoyan, D., Malapani, C., 2011. Intact and impaired cognitivecontrol processes in schizophrenia. Schizophr. Res. 126 (1), 132–137. Turner, M.L., Engle, R.W., 1989. Is working memory capacity task dependent? J. Mem. Lang. 28, 127–154. Watson, D., Clark, L.A., Tellegen, A., 1988. Development and validation of brief measures of positive and negative affect: the PANAS scales. J. Pers. Soc. Psychol. 54 (6), 1063–1070. Wechsler, D., 1981. The Wechsler Adult Intelligence Scale—Revised. Psychological Corporation, New York.
Contents lists available at SciVerse ScienceDirect
Schizophrenia Research journal homepage: www.elsevier.com/locate/schres
Is there an affective working memory deficit in patients with chronic schizophrenia? Nicola Mammarella a,⁎, Beth Fairfield a, Valeria De Leonardis a, Barbara Carretti b, Erika Borella b, Elisa Frisullo a, Alberto Di Domenico a a b
Department of Neuroscience and Imaging, University of Chieti, Italy Department of General Psychology, University of Padua, Italy
a r t i c l e
i n f o
Article history: Received 23 June 2011 Received in revised form 7 March 2012 Accepted 21 March 2012 Available online 15 April 2012 Keywords: Working memory Emotion Schizophrenia
a b s t r a c t Research interest in affective working memory has rapidly grown in the last decade. In this study we investigated working memory functions for affective and neutral words in a group of 22 patients with chronic schizophrenia and 22 healthy controls. In particular, participants were administered the operation working memory span task in which affective and neutral words had to be remembered. Results showed that patients made significantly more intrusion errors, recalling off-goal information, and showed poorer long-term memory performance than controls. In addition, affective trials showed the largest number of intrusion errors. These results suggest that a general attentional control deficit, especially over affective information, may underly failures to remember in chronic schizophrenia patients. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Emotion regulation skills are fundamental for many everyday activities since all individuals typically interact with valenced environments. Schizophrenia patients show remarkable impairments in Working Memory (WM) in both verbal and visuo-spatial domains (e.g., Quee et al., 2011) as well as in the integration between the two (e.g., Burglen et al., 2004; Lee and Park, 2005). However, most of these studies used neutral valenced information. Recently, a series of studies showed that schizophrenia patients are also impaired in the short maintenance and control over affective informantion. A study by Gard et al. (2011), for instance, found that schizophrenia patients had difficulties maintaining the intensity of previously presented emotional pictures in WM and that this occurred for both positive and negative pictures, while Habel et al. (2010) showed that schizophrenia patients had difficulties controlling negative emotional information during a n-back WM task (but see Diaz et al. (2011) for a different result), where negative pictures intefered with the participants'ability to compare target stimuli with preceeding ones. Nevertheless, the available data do not help to directly investigate the effect of affective information on WM performance, and to date, as far as we know, no studies have used a classical WM span task procedure to investigate affective information processing in schizophrenia. In typical WM span tasks (e.g., Daneman and Carpenter, 1980; Engle and Kane, 2004), participants are required to process (read and judge) a series of sentences, words or operations, and remember final words/digits in their correct serial order. These tasks have been shown to entail concurrent processing and short-term
storage demands coupled with an attentional control component (that might be indexed by the number of intrusion errors) to limit interference between processing and storage. Accordingly, in this study we compared WM performance in a group of chronic schizophrenia and healthy controls using an adaptation of the classical operation WM span task (Turner and Engle, 1989), widely used in clinical settings, in which affective words were used. The interesting methodological aspect of this work was to ensure active maintenance of affective to-be-remembered stimuli in WM by making participants process a series of arithmetic operations and remember only final target words (affective and neutral ones). In line with a well-established deficit in cognitive control (e.g., Smith et al., 2011), we expect schizophrenia patients to show a greater number of intrusion errors especially for affective stimuli compared to controls. In addition, a series of studies on healthy participants (e.g., Dreisbach and Goschke, 2004; Dreisbach, 2006; Rowe et al., 2007) found that positive emotions generally broad the focus of attention during the execution of a cognitive task, leading to processing of both relevant and irrelevant information. If so, intrusion errors should be particularly pronounced with positive trials. However, no studies, to our knowledge, have investigated this effect in schizophrenia patients. Therefore our work is an exploratory study aimed at verifying whether the same pattern of intrusion errors occurs in schizophrenia. 2. Materials and method 2.1. Participants
⁎ Corresponding author at: Department of Neuroscience and Imaging, University of Chieti, Italy. Tel.: + 39 0871 355 4204; fax: + 39 0871 355 4163. E-mail address: [email protected] (N. Mammarella). 0920-9964/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2012.03.028
Demographic and clinical data are summarized in Table 1. This study included 22 patients with chronic schizophrenia spectrum disorder and
100
N. Mammarella et al. / Schizophrenia Research 138 (2012) 99–101
Table 1 Demographic and clinical characteristics of patients and controls according to mean scores and standard deviations in parentheses. Chronic
Controls
N Age (years)
22 45.7 (7.7)
22 44.1 (4.8)
Gender Female Male Education (years) Paranoid Residual Duration of illness (years) Forward digit span Backward digit span
10 12 8.4 (3.3) 13 9 22.3 (7.5) 4.2 (1.2)a 5.1 (1.3)
10 12 9.7 (4.1)
PANAS Positive Negative PANSS total Positive total Negative total
29.8 17.8 66.4 15.0 18.0
Neuroleptic medication
No. of patients
Clozapine Haloperidol Aripiprazole Olanzapine Quetiapine Chlorpromazine
5 15 7 7 8 2
(7.5)a (4.4)a (15.3) (4.22) (6.15)
7.9 (1.8)a 7.2 (1.8)
21.7 (5.9) 18.0 (6.3)
a p b .05; the forward and backward digit span are from WAIS-R (Wechsler, 1981); the PANAS (Positive and Negative Affective Scale) is from Watson et al. (1988); the PANSS (Positive and Negative Syndrome Scale) is from Kay et al. (1987).
affective word database of 200 words developed in our lab and judged by an independent group of 100 students in terms of valence and arousal on a 9-point scale. The 28 positive words had a mean valence of 7.8 (1.5) and a mean arousal level of 5.9 (2.8); the 28 negative words had a mean valence of 2.4 (1.8) and a mean arousal level of 5.9 (2.7). Finally the 28 neutral words had a mean valence of 5.5 (1.9) and a mean arousal level of 2.7 (2.3). All valenced sets were presented to participants, that is, all span levels were administered. The order of the valenced set was counterbalanced across participants. Following the WM phase, an unexpected yes–no recognition memory task was presented. For the recognition memory test, working memory words were intermixed with new words. A total of 126 words were presented (28 old negative, 28 old positive, 28 old neutral and 42 new items with comparable valence and arousal levels as the target items used in the WM span: 14 negative, 14 positive and 14 neutral). Participants were asked to respond “yes” on a prepared grid if they remembered having experienced the word or “no” if they did not. 3. Results 3.1. Data analysis Test data were analyzed using Statistica 6.0 (Statsoft). We used mean proportional numbers of correct recalled words and mean proportional numbers of intrusions errors (i.e., number of recalled words from trials within the same set) as a function of valence as dependent WM measures. The correction criterion was correspondence between seen word and recalled word, in the correct position. Therefore, if a participant made a mistake in calculating the sum of an arithmetic operation but correctly recalled the seen word at the end of the trial, it was counted as a correct response unless the number of errors was above 15% of the total operations. For the recognition memory task, accuracy scores were computed as HITs − FAs. HITs are the proportion of old stimuli correctly recognized as old, while FAs are the proportion of new stimuli recognized as old. Results are presented in Table 2. Between-subjects comparisons within the patients's group did not reveal any significant differences linked to the type of schizophrenia in any considered measures. Accordingly, we collapsed patients' data. Lastly, it must be underlined that these data should be taken with caution as the number of participants does not allow strong statistical power.
22 non-psychiatric comparison participants. Patients were recruited from a chronic psychiatric unit. Diagnoses were made according to the DSM-IV criteria, as determined by the structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) (SCID), by a board-certified attending research team of psychiatrists. Twenty-two healthy adults were matched to patients for age, education and gender. They were recruited through University advertisements. No participants had a history of traumatic brain injury, epilepsy, alcoholism or substance abuse, other diagnosable neurological conditions or organic mental disorder, nor were they being treated with antidepressants, benzodiazepines or lithium. Additionally, controls were excluded if they reported past or present psychiatric disorders, as well as if a first-degree relative had sought psychiatric diagnosis or treatment. Before the experimental task, both groups received the PANAS to evaluate their baseline subjective mood. Schizophrenia patients reported a greater number of positive compared to negative emotions (p b .05), while no differences were detected between positive and negative mood in the control group.
The effect of group was not significant F(1,42) = 1.59 p = .20 as the number of correct words was .78 in the control group and .80 in the schizophrenia patients group. The valence effect was also not significant, F b 1, as both groups recalled a comparable number of affective (positive .80, negative .79) and neutral words (.79). Finally, the two-way interaction was not significant, F b 1.
2.2. Materials and procedure
3.3. Intrusions
The operation span task requires participants to solve a series of math operations while remembering a set of unrelated words. Participants were presented with one math operation at a time, centered on a computer screen followed by a target word. They solved the math problem and read the target word aloud. The operation-word strings were presented in sets of two to five items. Following each complete set, participants were cued to recall target words in the correct order of presentation (e.g. a two item set: (2 + 5) − 2 = 5, T/F? JOY; (7 − 2) + 3 = 6, T/F? LOVE, Recall: JOY, LOVE). Four sets of 4 different lengths (from 2 to 5) were constructed for each affective valence (positive, negative and neutral). Stimuli items for the operation span task consisted in 84 arithmetic operations and 84 target words. Words were selected from an
There was a significant effect of group F(1,42) = 47.42 p b .001, η 2 = .53, as schizophrenia patients made more intrusions (.15) compared to controls (.04). The effect of valence was also significant,
3.2. Correct recall
Table 2 Mean proportional scores of correct recalled words and intrusions in the emotion operation working memory span task as a function of group and valence. Standard deviations are in parentheses. Correct recall
Patients Controls
Intrusion errors
N
Positive
Negative
Neutral
Positive
Negative
Neutral
22 22
.81 (.11) .79 (.10)
.80 (.08) .77 (.10)
.80 (.09) .77 (.09)
.15 (.08) .05 (.04)
.16 (.07) .04 (.04)
.15 (.09) .02 (.03)
N. Mammarella et al. / Schizophrenia Research 138 (2012) 99–101
F(2,84) = 3.61 p b .01, η 2 = .10 as intrusions were typically more positive than neutral (p b .05). The two-way interaction was not significant, F b 1. 3.4. Recognition There was a significant effect of group F(1,42) = 45.79 p b .001 η 2 = .52, as controls were more accurate (.61) than patients (.31). The effect of valence was also significant, F(2,84) = 4.31 p b .05, η 2 = .09: negative words (.53) were recognized better than positive (.43) and neutral words (.42). Finally, the two-way interaction was not significant, F b 1. 4. Discussion One of the goals of the present study was to further clarify affective WM performance in chronic schizophrenia since intervention that can increase emotional WM may be beneficial as training for emotion regulation abilities. We found comparable recall of final target words across both groups when we considered the number of correctly recalled words. However, our data highlighted impaired WM performance in our affective operation span task in terms of a greater number of intrusion errors confirming the well-documented general attentional control and WM impairments in schizophrenia (e.g., Smith et al., 2011). The second important goal of our study was to investigate the role of valence within this WM paradigm. Thus, valence was manipulated in order to observe how schizophrenia patients control affective words. In line with previous studies (e.g., Hall et al., 2007), our results support the role of valence in their shortterm forgetting. In fact, although both groups showed valenced intrusion errors, these were particularly marked for schizophrenia. Retention in long-term memory also showed a unique contribution of valence as participants were more accurate in recognizing negative words compared with the other types of words and this was particularly true for schizophrenia patients. These long-term memory data are consistent with the WM data as deficient inhibitory attentional control over positive words later favored recognition for negative words (Hasher et al., 2007). In part, our findings are in line with a series of studies (e.g., Dreisbach and Goschke, 2004; Dreisbach, 2006; Rowe et al., 2007) which found a greater tendency to be distracted by positive rather than negative emotions. Our additional interpretation is that the greater number of positive intrusion errors in the patients group may be also due to their tendency to maintain a positive affective state. In fact, we found that patients reported more positive than negative moods. Altogether, our overall results are in line with a general attention control deficit in chronic schizophrenia, and suggest that affective information may increase their forgetting in WM. Role of funding source No funding sources were involved in this study.
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Contributors Authors Mammarella, Fairfield, Carretti and Borella all contributed to drafting the manuscript. Author Mammarella was both principal investigator and project director of the study. Authors Carretti and Borella designed the experimental protocol. Authors Borella and Frisullo were involved in experiment programming. Authors Di Domenico and Frisullo undertook statistical analyses. Authors De Leornardis and Fairfield were involved in data collection and data management. All authors have contributed to and have approved the final manuscript. Conflict of interest All authors declare that they have no conflicts of interest. Acknowledgements The authors are grateful to all those who participated in our research study.
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