Separating response‐execution bias from decision bias: Arguments for an additional parameter in Ratcliff's diffusion model

Diffusion model data analysis permits the disentangling of different processes underlying the effects of experimental manipulations. Estimates can be provided for the speed of information accumulation, for the amount of information used to draw conclusions, and for a decision bias. One parameter describes the duration of non‐decisional processes including the duration of motor‐response execution. In the default diffusion model, it is implicitly assumed that both responses are executed with the same speed. In some applications of the diffusion model, this assumption will be violated. This will lead to biased parameter estimates. Consequently, we suggest accounting explicitly for differences in the speed of response execution for both responses. Results from a simulation study illustrate that parameter estimates from the default model are biased if the speed of response execution differs between responses. A second simulation study shows that large trial numbers (N>1,000) are needed to detect whether differences in response‐execution times are based on different execution times.     

When do microsaccades follow spatial attention?

Following up on an exchange about the relation between microsaccades and spatial attention (Horowitz, Fencsik, Fine, Yurgenson, & Wolfe, 2007; Horowitz, Fine, Fencsik, Yurgenson, & Wolfe, 2007; Laubrock, Engbert, Rolfs, & Kliegl, 2007), we examine the effects of selection criteria and response modality. We show that for Posner cuing with saccadic responses, microsaccades go with attention in at least 75% of cases (almost 90% if probability matching is assumed) when they are first (or only) microsaccades in the cue—target interval and when they occur between 200 and 400 msec after the cue. The relation between spatial attention and the direction of microsaccades drops to chance level for unselected microsaccades collected during manual-response conditions. Analyses of data from four cross-modal cuing experiments demonstrate an above-chance, intermediate link for visual cues, but no systematic relation for auditory cues. Thus, the link between spatial attention and direction of microsaccades depends on the experimental condition and time of occurrence, but it can be very strong.     

Two types of serial dependence in visual working memory

Stimulus representations in working memory depend on memory traces of past stimuli both from previous trials and from the current trial. However, it is unclear whether the same or different mechanisms underlie this serial dependence across and within trials. We directly contrasted estimates of bias for pairs of immediately successive stimuli across and within trials. In each trial, participants memorized two consecutive motion direction stimuli (S1 and S2) and after a short delay were cued to report one of them. We found serial dependence across trials: The current S1 was attracted towards the preceding S2 when the latter had been cued for report. In contrast, within the same trial S2 was repulsed from S1. In addition, repulsion within a trial occurred for a broader range of motion direction differences between stimuli than attraction across trials. A second experiment in which 25% of trials did not require a response demonstrated that across‐trial attraction did not depend on whether the previous S2 actually had to be reported. Our findings provide evidence for two types of serial dependence operating across and within trials. They support the notion of different mechanisms integrating or segregating current from similar past memory contents depending on their task relevance.     

Do chimpanzees learn reputation by observation? Evidence from direct and indirect experience with generous and selfish strangers

Can chimpanzees learn the reputation of strangers indirectly by observation? Or are such stable behavioral attributions made exclusively by first-person interactions? To address this question, we let seven chimpanzees observe unfamiliar humans either consistently give (generous donor) or refuse to give (selfish donor) food to a familiar human recipient (Experiments 1 and 2) and a conspecific (Experiment 3). While chimpanzees did not initially prefer to beg for food from the generous donor (Experiment 1), after continued opportunities to observe the same behavioral exchanges, four chimpanzees developed a preference for gesturing to the generous donor (Experiment 2), and transferred this preference to novel unfamiliar donor pairs, significantly preferring to beg from the novel generous donors on the first opportunity to do so. In Experiment 3, four chimpanzees observed novel selfish and generous acts directed toward other chimpanzees by human experimenters. During the first half of testing, three chimpanzees exhibited a preference for the novel generous donor on the first trial. These results demonstrate that chimpanzees can infer the reputation of strangers by eavesdropping on third-party interactions.     

Blocked goals, persistent action: Implementation intentions engender tenacious goal striving

Research on goal attainment has demonstrated that people are more likely to reach their goals when they form implementation intentions. Three experiments tested whether implementation intentions lead to tenacious goal striving following blockage of an initial attempt to reach the goal. In all three experiments some participants were instructed to form an implementation intention and other participants were not. Subsequently, the initial goal-directed attempt of all participants was unexpectedly blocked. Experiment 1 found that implementation intentions resulted in more attempts to realize one’s goal. Experiment 2 showed that when participants formed an implementation intention their repeated attempt was acted out as intensely as their first, blocked attempt. Experiment 3 found that implementation intentions still allow people to seize an alternative, more onerous means to realize their intention. These results imply that implementation intention conserve self-regulatory strength. After goal blockage, the remaining strength can be used to continue goal-directed action.     

Die Effekte psychoanalytisch orientierter und verhaltenstherapeutischer Langzeittherapien

This prospective study compares 31 patients in behavior long-term-therapy (with an average of 63 sessions) with 31 patients in psychoanalytically-oriented long-term-therapy (with an average of 185 sessions) in a naturalistic design. All patients passed a diagnostic interview (SKID) by an external interviewer. Only patients with depression and anxiety problems (Axis I of DSM III – R) were included in the study. Symptoms (SCL-90-R), interpersonal problems (IIP-D) and goals (GAS) were examined at the beginning, after 1 year, after 2.5 and 3.5 years. We found that the characteristics of patients, who choose – or were referred to – psychoanalytically oriented or behaviour long term therapy were different, even when their diagnosis were comparable, in a number of characteristics, such as education, access to psychotherapy (recommended by professionals versus patients introduce themselves), the taking of psychotropic medication, and the strain of symptoms. The results demonstrate how research comparing therapies using parallelized samples do not meet reality in every case: Even if psychoanalists and behavior therapists do treat equal disorders, – and they each do that very successfully, as we could prove – the patients differ in many ways. Effect sizes and clinically significant results about changes of the symptomatic and of interpersonal problems are presented that prove the efficacy of the treatments.     

Stimulus and response conflict processing during perceptual decision making

Encoding and dealing with conflicting information is essential for successful decision making in a complex environment. In the present fMRI study, stimulus conflict and response conflict are contrasted in the context of a perceptual decision-making dot-motion discrimination task. Stimulus conflict was manipulated by varying dot-motion coherence along task-relevant and task-irrelevant dimensions. Response conflict was manipulated by varying whether or not competing stimulus dimensions provided evidence for the same or different responses. The right inferior frontal gyrus was involved specifically in the resolution of stimulus conflict, whereas the dorsal anterior cingulate cortex was shown to be sensitive to response conflict. Additionally, two regions that have been linked to perceptual decision making with dot-motion stimuli in monkey physiology studies were differentially engaged by stimulus conflict and response conflict. The middle temporal area, previously linked to processing of motion, was strongly affected by the presence of stimulus conflict. On the other hand, the superior parietal lobe, previously associated with accumulation of evidence for a response, was affected by the presence of response conflict. These results shed light on the neural mechanisms that support decision making in the presence of conflict, a cognitive operation fundamental to both basic survival and high-level cognition.     

Myopic regret avoidance: Feedback avoidance and learning in repeated decision making

Decision makers can become trapped by myopic regret avoidance in which rejecting feedback to avoid short-term outcome regret (regret associated with counterfactual outcome comparisons) leads to reduced learning and greater long-term regret over continuing poor decisions. In a series of laboratory experiments involving repeated choices among uncertain monetary prospects, participants primed with outcome regret tended to decline feedback, learned the task slowly or not at all, and performed poorly. This pattern was reversed when decision makers were primed with self-blame regret (regret over an unjustified decision). Further, in a final experiment in which task learning was unnecessary, feedback was more often rejected in the self-blame regret condition than in the outcome regret condition. We discuss the findings in terms of a distinction between two regret components, one associated with outcome evaluation, the other with the justifiability of the decision process used in making the choice.