Inaugural editorial.

In this inaugural editorial, Isabel Gauthier, the incoming editor of the Journal of Experimental Psychology: Human Perception and Performance, introduces the new team of associate editors and discusses increasing women's representation on the editorial board as one of her first priorities. Gauthier also discusses her concerns with the publication process and beliefs about the changes that may be needed. (PsycINFO Database Record

Researchers' choice of the number and range of levels in experiments affects the resultant variance-accounted-for effect size.

In psychology, the reporting of variance-accounted-for effect size indices has been recommended and widely accepted through the movement away from null hypothesis significance testing. However, most researchers have paid insufficient attention to the fact that effect sizes depend on the choice of the number of levels and their ranges in experiments. Moreover, the functional form of how and how much this choice affects the resultant effect size has not thus far been studied. We show that the relationship between the population effect size and number and range of levels is given as an explicit function under reasonable assumptions. Counterintuitively, it is found that researchers may affect the resultant effect size to be either double or half simply by suitably choosing the number of levels and their ranges. Through a simulation study, we confirm that this relation also applies to sample effect size indices in much the same way. Therefore, the variance-accounted-for effect size would be substantially affected by the basic research design such as the number of levels. Simple cross-study comparisons and a meta-analysis of variance-accounted-for effect sizes would generally be irrational unless differences in research designs are explicitly considered.

Effect of a one-session ACT protocol in disrupting repetitive negative thinking: a randomized multiple-baseline design

Repetitive negative thinking (RNT) in the form of worry and rumination has been robustly identified as a transdiagnostic process implicated in the onset and maintenance of emotional disorders. Recent research suggests that both forms of RNT are particularly counterproductive experiential avoidance strategies because individuals usually engage in them as the first response when experiencing distress. This leads to the extension of relational networks and discomfort as well as to the engagement in additional experiential avoidance strategies that soon provoke meaningful life limitations. The current study analyzed the effect of a one-session Acceptance and Commitment Therapy (ACT) protocol in reducing RNT through altering the discriminative functions of the most relevant self-related thought to engage in RNT. We used a two-arm, randomized multiple-baseline design. Participants were 11 adults experiencing RNT that had interfered with their functioning for at least the last six months and were suffering from moderate emotional symptoms. Four RNT-related measures were administered: a daily RNT self-register, measures of pathological worry, rumination (brooding), and frequency of negative thoughts. Nine participants showed significant reductions in at least three out of the four RNT measures during the 6-week follow-up. Effect sizes were very large in all RNT-related measures and in emotional symptoms, experiential avoidance, cognitive fusion, and valued living. Testing an ACT version for emotional disorders specifically focused on disrupting RNT is warranted (AU)

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Transfer of conditioned fear-potentiated startle across equivalence classes. An exploratory study

Research on fear conditioning is key to understanding the genesis and maintenance of anxiety disorders. A still scarce but growing evidence shows that fear-conditioned arousal reactions may transfer amongst physically dissimilar but symbolically related (e.g. equivalent) stimuli. The limited investigation published to date has relied on skin conductance responses as its main measure. Thus far, no published studies have analyzed this phenomenon using more emotionally sensitive psychophysiological measures, like fear-potentiated startle. Twenty-seven participants underwent a matching-to-sample procedure for the formation of two four-member equivalence classes (A1-B1-C1-D1 and A2-B2-C2-D2). Then, one element from each class was used in a differential aversive conditioning procedure (CS+: B1; CS-: B2) with electric shock as the UCS. Eye-blink startle (measured as EMG activity of the orbicularis oculi muscle after a burst of white noise), skin conductance responses, and shock-risk self-report ratings were collected. Results show no evidence of transfer of functions with any of the psychophysiological measures. A weak, inconclusive effect was observed for self-reported ratings (AU)

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Unpacking insanity defence standards: an experimental study of rationality and control tests in criminal law / Descifrar los criterios de defensa de la vesania: estudio experimental de las pruebas de racionalidad y control en derecho penal

The present study investigated the impact of different legal standards on mock juror decisions concerning whether a defendant was guilty or not guilty by reason of insanity. Undergraduate students (N=477) read a simulated case summary involving a murder case and were asked to make an insanity determination. The cases differed in terms of the condition of the defendant (rationality deficit or control deficit) and the legal standard given to the jurors to make the determination (Model Penal Code, McNaughten or McNaughten plus a separate control determination). The effects of these variables on the insanity determination were investigated. Jurors also completed questionnaires measuring individualism and hierarchy attitudes and perceptions of facts in the case. Results indicate that under current insanity standards jurors do not distinguish between defendants with rationality deficits and defendants with control deficits regardless of whether the legal standard requires them to do so. Even defendants who lacked control were found guilty at equal rates under a legal standard excusing rationality deficits only and a legal standard excluding control and rationality deficits. This was improved by adding a control test as a partial defence, to be determined after a rationality determination. Implications for the insanity defence in the Criminal Justice System are discussed (AU)

Este estudio ha investigado la repercusión de los diversos cánones legales en las decisiones simuladas acerca de si un acusado es culpable o no por motivos de vesania. Una muestra de 477 estudiantes universitarios leyeron el resumen de caso relativo a un asesinato, pidiéndoseles luego que determinasen si había enajenación mental. Los casos diferían en cuanto a la condición del acusado (déficit de racionalidad o de control) y el criterio legal proporcionado a los jurados para que tomaran la determinación (Código penal modelo, McNaughten o McNaughten mas una determinación sobre el control). Se investigó el efecto de estas variables en la determinación de vesania. Los jurados rellenaron también cuestionarios que medían actitudes de individualismo y jerarquía y la percepción de los hechos del caso. Los resultados indican que con los criterios de demencia actuales los jurados no distinguen entre acusados con déficit de racionalidad y aquellos con déficit de control, aunque los criterios legales se lo exijan. Incluso los acusados que carecían de control fueron hallados culpables en la misma proporción con un criterio legal que disculpaba el déficit de racionalidad y con otro que excluía los déficit de control y racionalidad. Consiguió mejorarse añadiendo una prueba de control como defensa parcial a determinar tras la decisión sobre la racionalidad. Se comentan las implicaciones para la defensa de la enajenación mental en el sistema de justicia penal (AU)

A review of cognitive inhibition in adults with unipolar depression

Although it is generally accepted that systematic processing biases are associated with depressive episodes, what is less well understood are the mechanisms responsible for such negative cognitive biases. Overall, empirical evidence has suggested that cognitive inhibitory deficits of emotional processing may play a central role in the onset and maintenance of depression. Thus, research has begun to investigate cognitive inhibition, a mechanism proposed to be fundamental to the negative cognitive biases evidenced within depression. These investigations may help to fill these gaps in the literature. The aim of the current paper was to provide a comprehensive review of the literature related to cognitive inhibition and investigate the evidence supporting the role of cognitive inhibition in the development and maintenance of major depressive disorder. Relevant research is reviewed and the current methods for examining cognitive inhibition are discussed. Furthermore, the implications of these results for research examining selective attention within depression are considered (AU)

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How do Scrabble players encode letter position during reading? / ¿Cómo codifican los jugadores de Scrabble la posición de las letras durante la lectura?

BACKGROUND: A number of experiments with skilled adult readers have shown that a transposed-letter pseudoword (e.g., CHOLOCATE) is considerably more word-like than a control replacement-letter pseudoword (e.g., CHOTONATE). For instance, in lexical decision, response times are longer and less accurate for CHOLOCATE than for CHOTONATE (i.e., a transposed-letter effect). METHOD: Here, we examined how letter position coding is attained in individuals who excel in orthographic-lexical processing: competitive Scrabble players. To this end, we conducted a lexical decision experiment with two types of pseudowords (transposedletter vs. replacement-letter pseudowords). RESULTS: Data showed that while the transposed-letter effect does occur in expert Scrabble players, the magnitude of the effect is dramatically smaller than in a control group of university students-in particular, for the accuracy data. CONCLUSIONS: The parameters responsible for the flexibility of letter position coding in models of visual word recognition must be modulated by the degree of expertise in orthographic-lexical processing

ANTECEDENTES: en experimentos con lectores adultos, las pseudopalabras creadas por transposición de letras (v.g., CHOLOCATE) se confunden frecuentemente con su palabra base. Por ejemplo, en tareas de decisión léxica ('¿es el estímulo una palabra?'), los tiempos de respuesta son mayores y con mayor porcentaje de errores para CHOLOCATE que para su control ortográfico CHOTONATE (es decir, un efecto de transposición de letras). MÉTODO: en el presente experimento examinamos los procesos de codificación de la posición de las letras en individuos particularmente expertos en el procesamiento ortográfico-léxico: jugadores de Scrabble de competición. Para ello, se realizó un experimento de decisión léxica con dos tipos de pseudopalabras (vía transposición de letras [CHOLOCATE] vs. vía sustitución de letras [CHOTONATE]). RESULTADOS: si bien los jugadores expertos de Scrabble muestran un efecto de transposición de letras, la magnitud del efecto es mucho menor que en estudiantes universitarios no entrenados a Scrabble, en particular para los datos de precisión. CONCLUSIONES: en los modelos de reconocimiento visual de palabras, la flexibilidad en la codificación de la posición de las letras en palabras debe ser modulada por la destreza en el procesamiento ortográfico-léxico

A discussion of alternatives for establishing empirical benchmarks for interpreting single-case effect sizes / Discusión de diferentes maneras de establecer criterios interpretativos empíricos para tamaños del efecto de diseños de caso único

In this paper we reflect on the numerous calls for the development of benchmarks for interpreting effect size indices, reviewing several possibilities. Such benchmarks are aimed to provide criteria so that analysts can judge whether the size of the effect o bserved is rather "small", "medium" or "large". The context of this discussion is single-case experimental designs, for which a great variety of procedures have been proposed, with their different nature (e.g., being based on amount of overlap vs. a standardized mean difference) posing challenges to interpretation. For each of the alternatives discussed we point at their strengths and limitations. We also comment how such empirical benchmarks can be obtained, usually by methodologists, and illustrate how these benchmarks can be used by applied researchers willing to have more evidence on the magnitude of effect observed and not only whether an effect is present or not. One of the alternatives discussed is a proposal we make in the current paper. Although it has certain limitations, as all alternatives do, we consider that it is worth discussing it and the whole set of alternatives in order to advance in interpreting effect sizes, now that computing and reporting their numerical values is (or is expected to be) common practicIn this paper we reflect on the numerous calls for the development of benchmarks for interpreting effect size indices, reviewing several possibilities. Such benchmarks are aimed to provide criteria so that analysts can judge whether the size of the effect o bserved is rather «small», «medium» or «large». The context of this discussion is single-case experimental designs, for which a great variety of procedures have been proposed, with their different nature (e.g., being based on amount of overlap vs. a standardized mean difference) posing challenges to interpretation. For each of the alternatives discussed we point at their strengths and limitations. We also comment how such empirical benchmarks can be obtained, usually by methodologists, and illustrate how these benchmarks can be used by applied researchers willing to have more evidence on the magnitude of effect observed and not only whether an effect is present or not. One of the alternatives discussed is a proposal we make in the current paper. Although it has certain limitations, as all alternatives do, we consider that it is worth discussing it and the whole set of alternatives in order to advance in interpreting effect sizes, now that computing and reporting their numerical values is (or is expected to be) common practice

El presente trabajo responde a la necesidad expresada de desarrollar criterios interpretativos para los índices de tamaño del efecto, repasando diferentes maneras para conseguirlo. El objetivo de los criterios es proporcionar herramientas a los analistas para que éstos puedan valorar si el efecto observado en su estudio es más bien «pequeño», «mediano» o «grande». El contexto en el cual tiene lugar la discusión son los diseños de caso único, para los cuales se ha propuesto una gran variedad de técnicas analíticas cuya base diferente (e.g., grado de solapamiento versus diferencia de medias estandarizada) supone un reto para la interpretación. Para cada una de las alternativas que se comentan, se destacan las ventajas e inconvenientes. Adicionalmente, se comenta cómo estos criterios pueden ser obtenidos, una tarea propia de los metodólogos, y cómo pueden ser utilizados por investigadores aplicados que desean disponer de más evidencias sobre la magnitud del efecto observado, más allá de decidir si el efecto existe o no. Una de las alternativas es una propuesta que se realiza en el marco del presente artículo. A pesar de que también presenta desventajas, como todas las alternativas, consideramos que es necesario discutir esta alternativa y todas las demás con la finalidad de avanzar en la interpretación de tamaños del efecto, en un momento en el cual el hecho de calcular y reportar sus valores numéricos es (o se supone) habitual

Focus on your breathing: does meditation help lower rumination and depressive symptoms?

The present study examines the relationships between meditation, rumination and depressive symptoms. Research to date has found that individuals who meditate experience less ruminative thinking and have lower depressive symptoms than individuals who do not meditate. While most psychological studies in this area examined the influence of controlled attention focused therapies on rumination and depression, this study describes the relationships between these indices in a non-clinical population. We hypothesize that: 1) The longer meditators practice meditation, the less they will experience ruminative thinking and depressive symptoms; 2) Meditators will have less ruminative thinking and depressive symptoms than non-meditators; 3) Different measures of meditation and ruminative thinking will negatively predict depressive symptoms; and 4) The relation between ruminative thinking and depressive symptoms will be positive and stronger among non-meditators than among meditators. 150 participants, about half of them practicing meditation, were sampled via social networks and answered questions pertaining to ruminative thinking, depressive symptoms and their meditation practice. Participants who practiced meditation for a longer period of time reported less rumination and depressive symptoms. Furthermore, meditators experienced significantly less ruminative thinking (but not depressive symptoms) than non-meditators. Moreover, rumination was found to positively predict depressive symptoms, while meditation measures did not. Finally, the relationship between ruminative thinking and depressive symptoms was found to be positive, significant and stronger among non-meditators than among meditators. Persistent meditation may have long lasting effects on lowering ruminative thinking and depressive symptoms (AU)

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Discriminaciones condicionales con estímulos contextuales versus complejos: implicaciones en la transferencia del aprendizaje / Conditional discriminations using contextual versus complex stimuli: implication for learning transfer

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This study sought to determine the effect of two conditional discrimination procedures involving contextual vs complex stimuli, on two types of learning transfer. For this purpose, three experiments were carried out. The first experiment used a contextual control procedure and the second a complex control procedure. The third experiment compared the two procedures using an inter-group design. The first two experiments aimed to determine the effect of the teaching procedure used on the transfer of learning to new stimulus relations (first type of transfer). The third experiment sought to determine the effect of teaching conditional discriminations using wither contextual or complex stimuli on the other discrimination (second type of transfer). In the first experiment, four out of six subjects displayed transfer of learning to new stimulus relations; in the second, only two subjects displayed that transfer. In the third experiment, statistically-significant differences were recorded for the dependent variable: successful attempts in the test using contextual stimuli. The teaching of tasks using contextual stimuli appears to favour the transfer of learning to conditional discriminations involving complex stimuli; the reverse, however, is not true to the same extent. These findings may be useful for the teaching of complex discriminations to intellectually-disabled or autistic children (AU)

The Idiographic Approach in Psychological Research. The Challenge of Overcoming Old Distinctions Without Risking to Homogenize.

In this paper I discuss the relevance of the single-case approach in psychological research. Based upon work by Hurtado-Parrado and López-López (Integrative Psychological and Behavioral Science, 2015), who outlined the possibility that Single-Case Methods (SCMs) could be a valid alternative to Null Hypothesis Significance Testing (NHST), I introduce the idiographic approach (Salvatore and Valsiner Theory & Psychology, 20(6), 817-833, 2010; Valsiner Cultural & Psychology, 20(2), 147-159, 2014; Salvatore Culture & Psychology, 20(4), 477-500, 2014) based on the logic of abductive generalization, rather than the logic of inductive generalization. I present the theoretical, epistemological and methodological assumptions that this approach proposes; in particular, I discuss the re-conceptualization of some now obsolete rigid opposition, the inconsistency of sample use in psychological research, the relationship between uniqueness and general, the relationship between theory and phenomena, and finally the validation process.

Efficiency of arithmetic procedures modulates the problem-size effect in subtraction

The aim of this study was to examine whether differences in strategy selection and/or strategy efficiency can explain the modulation of the problem-size effect by arithmetic skill. More specifically, we wondered whether arithmetic skill increases the use of retrieval strategy in large problems, and/or enhances the efficiency of either retrieval or procedural strategies. The performance of highly-skilled (HS) and less highly-skilled (LS) individuals on a subtraction verification task was analyzed according to problem size and to the strategy reported on a trial-by-trial basis after each problem. The problem size effect was larger for LS individuals than for their HS peers, both in response time and in hit rate. Nevertheless, groups did not differ regarding the strategy reported for each subtraction size. As expected, problems in which retrieval strategy was reported were solved more quickly and more accurately than problems solved by procedural strategies. Responses using retrieval strategy were equally fast in the two groups, but HS individuals performed better than LS when using procedural strategies. The results therefore suggest that the differences in behavioral measures between groups might specifically be due to differences in the efficiency of procedural strategies (AU)

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The role of derivative suffix productivity in the visual word recognition of complex words / El papel de la productividad de los sufijos derivativos en el reconocimiento visual de palabras complejas

In this article we present two lexical decision experiments that examine the role of base frequency and of derivative suffix productivity in visual recognition of Spanish words. In the first experiment we find that complex words with productive derivative suffixes result in lower response times than those with unproductive derivative suffixes. There is no significant effect for base frequency, however. In experiment two, the same procedure was undertaken with pseudowords, showing that when they are composed by productive derivative suffixes they take longer to be rejected than when they are composed by unproductive derivative suffixes. Again, the role of base frequency fails to reach significance. These results endorse the view that derivative suffixes have a relevant role in visual recognition of complex words. According to our results, derivative suffixes create the conditions for taking a lexical candidate as a legal lexical entry and therefore they contribute decisively to the lexical decision (AU)

En este artículo presentamos dos experimentos de decisión léxica que examinan el rol de las variables de frecuencia de base y de la productividad de los sufijos derivativos en el reconocimiento visual de las palabras. En el primer experimento encontramos que las palabras complejas con sufijos derivativos productivos tardan menos tiempo en ser respondidas que aquellas otras con sufijos derivativos improductivos. Se observa también la falta de significación para la frecuencia de base. En el experimento dos se lleva a cabo la misma metodología pero con pseudopalabras, mostrando que cuando éstas están compuestas por sufijos derivativos productivos tardan más tiempo en ser rechazadas que cuando están compuestas por sufijos derivativos improductivos. De nuevo la variable de frecuencia de base no alcanza valor significativo. Estos resultados respaldan la visión de que los sufijos derivativos tienen un rol relevante en el reconocimiento visual de las palabras complejas. De acuerdo a nuestros resultados, los sufijos derivativos crean las condiciones para tomar un candidato como una entrada léxica legal y por lo tanto contribuyen decisivamente a la decisión léxica. Estos resultados se interpretan finalmente a la luz de estudios previos centrados en las mismas variables (AU)

Spontaneous recovery of human spatial memory in a virtual water maze / Recuperación espontánea de la memoria espacial en humanos en un laberinto virtual de agua

The occurrence of spontaneous recovery in human spatial memory was assessed using a virtual environment. In Experiment 1, spatial memory was established by training participants to locate a hidden platform in a virtual water maze using a set of four distal landmarks. In Experiment 2, after learning about the location of a hidden platform, the platform was placed in new position within the virtual water maze in order to extinguish the original learning. An immediate test showed that participants searched for the platform at its most recent location. In contrast, on a delayed test (24 h), participants tended to seek the platform at the original location. These findings are consistent with the spontaneous recovery effect on spatial memory and are discussed in relation to the cognitive map theory and associative approach of spatial memory (AU)

Se investigó la ocurrencia de recuperación espontánea de l memoria espacial en humanos expuestos a un entorno virtual. En el Experimento 1 la memoria espacial fue establecida por entrenar a los participantes a localizar una plataforma oculta en un laberinto virtual de agua empleando un conjunto de cuatro claves distales. En el Experimento 2,tras el aprendizaje sobre la localización de la plataforma, ésta se ocultó en un sitio novedoso dentro del laberinto virtual de agua a fin de extinguir el aprendizaje original. Una prueba inmediata mostró que los participantes buscaron la plataforma en sumás reciente ubicación. En cambio, en una prueba demorada (24 h), los participantes tendieron a buscar la plataforma en el sitio en el que originalmente se colocó. Estos resultados son consistentes con un efecto de recuperación espontánea de la memoria espacial y son discutidos en relación a la teoría del mapa cognitivo y a la aproximación asociativa de la memoria espacial (AU)

Power and sample size calculations for testing linear combinations of group means under variance heterogeneity with applications to meta and moderation analyses

The general formulation of a linear combination of population means permits a wide range of research questions to be tested within the context of ANOVA. However, it has been stressed in many research areas that the homogeneous variances assumption is frequently violated. To accommodate the heterogeneity of variance structure, the Welch–Satterthwaite procedure is commonly used as an alternative to the t test for detecting the substantive significance of a linear combination of mean effects. This article presents two approaches to power and sample size calculations for the Welch–Satterthwaite test. The usefulness and diversity of the suggested techniques are illustrated with two of the potential applications in meta and moderation analyses. The numerical assessments showed that the proposed approaches outperform the existing methods on the accuracy of power calculations and sample size determinations for meta and moderation studies. Computer algorithms are also developed to implement the recommended procedures in actual research designs (AU)

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A combined IRT and SEM approach for individual-level assessment in test-retest studies / Un enfoque combinado TRI-MEE para la evaluación individual enestudios test-retest

The standard two-wave multiple-indicator model (2WMIM) commonly used to analyze test-retest data provides information at both the group and item level. Furthermore, when applied to binary and graded item responses, it is related to well-known item response theory (IRT) models. In this article the IRT-2WMIM relations are used to obtain additional information for each individual respondent. Procedures are proposed for (a) obtaining individual estimates of trait levels and amount of change, and (b) assessing whether the main assumptions on which these estimates are based are met. The procedures are organized in a comprehensive approach that can be used with binary, graded, and continuous responses. The relevance of the proposal is discussed and guidelines are given on how to use the approach in applied research. Finally, the approach is illustrated with an empirical data set. It worked well and provided meaningful information (AU)

El modelo longitudinal de medida con múltiples indicadores evaluados en dos ocasiones (MI2O) se utiliza habitualmente en estudios test-retest y proporciona información al nivel de grupo y al nivel de ítems. Además, cuando se aplica a respuestas binarias o graduadas dicho modelo se convierte en una extensión de algunos modelos básicos de teoría de respuesta al ítem (TRI). En este artículo se explotan las relaciones TRI-MI2O para obtener información adicional al nivel de cada individuo. Se proponen procedimientos para (a) obtener estimaciones individuales de niveles en el rasgo y magnitud del cambio, y (b) evaluar si se cumplen o no los supuesto básicos en que dichas estimaciones se fundamentan. Los procedimientos propuestos se organizan en un marco general que puede utilizarse con respuestas binarias, graduadas o continuas. Se discute la relevancia de la propuesta y se proponen recomendaciones para utilizarla en investigación aplicada. Finalmente, la propuesta se ilustra con un ejemplo empírico donde funcionó bien y proporcionó información útil (AU)

Contrasting ABA, AAB and ABC renewal in a free operant procedure

One experiment used a free operant procedure with rats to compare ABA, AAB and ABC renewal by using a within-subject testing procedure. All rats were first trained to press a lever for food in context A. Lever pressing was then extinguished in either context A or context B. For rats in the groups ABA and ABC extinction took place in context B, while the rats in group AAB received extinction in the same context in which acquisition took place (context A). Finally, all rats were tested for renewal in two sessions. One extinction session was carried out in the same extinction context and another session in a different context. Rats in the group ABA were tested in context B and in context A; rats in the group AAB were tested in contexts A and B, whereas the group ABC was tested in contexts B and C. The results of the ANOVA showed context renewal since all groups had higher rates of responding when they were tested outside the extinction context, F(2, 21) = 15.32, p = .001, ηp 2 = .59; however, AAB and ABC renewal was lesser than ABA renewal, F(1, 21) = 16.70, p = .0001, ηp 2 = .61 (AU)

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Wolfgang Köhler's the mentality of apes and the animal psychology of his time

In 1913, the Anthropoid Station for psychological and physiological research in chimpanzees and other apes was founded by the Royal Prussian Academy of Sciences (Berlin) near La Orotava, Tenerife. Eugene Teuber, its first director, began his work at the Station with several studies of anthropoid apes’ natural behavior, particularly chimpanzee body language. In late 1913, the psychologist Wolfgang Köhler, the second and final director of the Station, arrived in Tenerife. During his stay in the Canary Islands, Köhler conducted a series of studies on intelligent behavior in chimpanzees that would become classics in the field of comparative psychology. Those experiments were at the core of his book Intelligenzprüfungen an Menschenaffen (The Mentality of Apes), published in 1921. This paper analyzes Köhler's experiments and notions of intelligent behavior in chimpanzees, emphasizing his distinctly descriptive approach to these issues. It also makes an effort to elucidate some of the theoretical ideas underpinning Köhler's work. The ultimate goal of this paper is to assess the historical significance of Köhler's book within the context of the animal psychology of his time (AU)

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The effect of the emotive decisions in prospect theory

The main purpose of this paper was to show that the certainty and reflection effects of prospect theory do not occur when stimuli have an affective value. To this end, 160 participants were asked to reply to a series of problems originally designed by Kahneman and Tversky (1979), but modified according to the contributions of Rottenstreich and Hsee (2001). The sample was divided into four experimental conditions, two in a gain situation and two in a loss situation. In both cases, affect-rich and affect-poor stimuli were applied in sure and probable alternatives. The findings showed that, in agreement with our hypotheses, the affective value of the stimuli altered the outcome predicted by prospect theory, showing response patterns contrary to certainty and reflection effects (p ≤ .01 and p ≤ .05 respectively). Therefore, his research supports the influence of the emotions in the decision-making process, and should be extended to other aspects of prospect theory (AU)

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