Assessing intentional binding with the method of constant stimuli

Intentional binding describes the phenomenon that actions and their effects are perceived to be temporally approximated. We introduced a new method of duration estimation to the research field, the method of constant stimuli. Participants freely chose to press one of two keys or experienced passive key presses. After an interval of 250ms or 600ms a visual effect occurred. In Experiment 1, each key produced an effect after a specific interval. In Experiment 2, both keys produced an effect after the same interval that varied between sessions. Participants compared the duration of the action-effect interval with a tone of varying duration. To assess intentional binding, we compared the perceived duration of the action-effect interval between the active and passive condition. We showed intentional binding for 600ms, but not for 250ms action-effect intervals in both experiments. Thus, the method of constant stimuli is suitable to assess intentional binding.     

Associative memory or algorithmic search: a comparative study on learning strategies of bats and shrews

Two common strategies for successful foraging are learning to associate specific sensory cues with patches of prey ("associative learning") and using set decision-making rules to systematically scan for prey ("algorithmic search"). We investigated whether an animal's life history affects which of these two foraging strategies it is likely to use. Natterer's bats (Myotis nattereri) have slow life-history traits and we predicted they would be more likely to use associative learning. Common shrews (Sorex araneus) have fast life-history traits and we predicted that they would rely more heavily on routine-based search. Apart from their marked differences in life-history traits, these two mammals are similar in body size, brain weight, habitat, and diet. We assessed foraging strategy, associative learning ability, and retention time with a four-arm maze; one arm contained a food reward and was marked with four sensory stimuli. Bats and shrews differed significantly in their foraging strategies. Most bats learned to associate the sensory stimuli with the reward and remembered this association over time. Most shrews searched the maze using consistent decision-making rules, but did not learn or remember the association. We discuss these results in terms of life-history traits and other key differences between these species. Our results suggest a link between an animal's life-history strategy and its use of associative learning.     

Personality and relationship quality during the transition from high school to early adulthood

The post-high school transition period is believed to be associated with considerable changes in social networks, yet longitudinal studies documenting these changes are scarce. To address this gap, the current research explored 3 relevant issues. First, changes in participants' relationship characteristics during the transition from high school were examined. Second, the roles of personality traits as antecedents of these changes were studied. Third, the association between change in relationship characteristics and personality during the transition was explored. A sample of over 2,000 German emerging adults, surveyed before leaving school and then 2 years after the transition from high school, was assessed on personality traits and a multidimensional assessment of the quality of their relationships. Findings indicated that participants experienced mostly positive changes in relationship quality during the transition from high school and that antecedent personality at school was an important predictor of the nature of this change. Finally, change in relationship quality was found to be associated with personality change during the post-school transition. Findings indicated that personality traits may influence transition success and that change in relationships during this transition may influence personality development. The implications of the research for post-school transition success are discussed.     

A facial expression for anxiety

Anxiety and fear are often confounded in discussions of human emotions. However, studies of rodent defensive reactions under naturalistic conditions suggest anxiety is functionally distinct from fear. Unambiguous threats, such as predators, elicit flight from rodents (if an escape-route is available), whereas ambiguous threats (e.g., the odor of a predator) elicit risk assessment behavior, which is associated with anxiety as it is preferentially modulated by anti-anxiety drugs. However, without human evidence, it would be premature to assume that rodent-based psychological models are valid for humans. We tested the human validity of the risk assessment explanation for anxiety by presenting 8 volunteers with emotive scenarios and asking them to pose facial expressions. Photographs and videos of these expressions were shown to 40 participants who matched them to the scenarios and labeled each expression. Scenarios describing ambiguous threats were preferentially matched to the facial expression posed in response to the same scenario type. This expression consisted of two plausible environmental-scanning behaviors (eye darts and head swivels) and was labeled as anxiety, not fear. The facial expression elicited by unambiguous threat scenarios was labeled as fear. The emotion labels generated were then presented to another 18 participants who matched them back to photographs of the facial expressions. This back-matching of labels to faces also linked anxiety to the environmental-scanning face rather than fear face. Results therefore suggest that anxiety produces a distinct facial expression and that it has adaptive value in situations that are ambiguously threatening, supporting a functional, risk-assessing explanation for human anxiety.     

The ability of children to delay gratification in an exchange task

The ability to wait for a reward is a necessary capacity for economic transactions. This study is an age-related investigation of children's ability to delay gratification in an exchange task requiring them to wait for a significant reward. We gave 252 children aged 2-4 a small piece of cookie, then offered them an opportunity to wait for a predetermined delay period before exchanging it for a larger one. In a first experiment, the children had to exchange the initial food item for rewards two, four or eight times larger. Results showed that children aged 3-4 years old sustained longer time lags for larger rewards than for smaller rewards. This effect was not found in 2-year-old subjects. In a second experiment, a reward 40 times larger than the initial piece was offered to determine the maximum waiting time that children could sustain. All age groups increased their performances. Older children were more successful at waiting, but some children as young as 2 years old were able to tolerate delays of up to 16 min. Older children who chose to give up waiting earlier than their known capacity demonstrated anticipation skills which had not been seen in younger children, showing that they had anticipated an increase in the time lag, and that they had considered both time and reward value when making their decision. Despite the age effect, we did not establish any limits for delaying gratification in children. This study may have educational implications for dealing with behavioral misconduct, which is known to be related to impulsivity control in young children.     

The compensation and capitalization models: A test of two approaches to individualizing the treatment of depression

Despite long-standing calls for the individualization of treatments for depression, modest progress has been made in this effort. The primary objective of this study was to test two competing approaches to personalizing cognitive-behavioral treatment of depression (viz., capitalization and compensation). Thirty-four adults meeting criteria for Major Depressive Disorder (59% female, 85% Caucasian) were randomized to 16-weeks of cognitive-behavioral treatment in which strategies used were selected based on either the capitalization approach (treatment matched to relative strengths) or the compensation approach (treatment matched to relative deficits). Outcome was assessed with a composite measure of both self-report (i.e., Beck Depression Inventory) and observer-rated (i.e., Hamilton Rating Scale for Depression) depressive symptoms. Hierarchical linear modeling revealed a significant treatment approach by time interaction indicating a faster rate of symptom change for the capitalization approach compared to the compensation approach (d = .69, p = .03). Personalizing treatment to patients' relative strengths led to better outcome than treatment personalized to patients' relative deficits. If replicated, these findings would suggest a significant change in thinking about how therapists might best adapt cognitive-behavioral interventions for depression for particular patients.     

Cost–benefit and distributional analyses of accessory stimuli

Accessory stimuli (AS) are task-irrelevant events (typically an auditory tone) that speed reaction time (RT). With two conditions (AS-present, AS-absent) it is unclear whether AS-presence causes benefits or AS-absence causes costs, possibly due to the expectancy violations. The current study added a third condition where AS were absent in blocks and not expected (pure blocks); in other blocks, AS occurred with a probability of 0.5 (mixed blocks), allowing cost-benefit analysis comparing AS-absent RTs in pure and mixed blocks. Results demonstrated RTs were slower when AS were absent, regardless of whether the absence occurred in a mixed block or a pure block, suggesting AS do provide a benefit to RT. Additionally, AS-facilitation across the RT distribution was analysed using cumulative distribution frequencies and ex-Gaussian parameter estimation. Both provided converging evidence that AS-facilitation increases towards the slower end of the RT distribution. The implications for the utility of AS paradigms are discussed.     

Real three-dimensional objects: effects on mental rotation

The current experiment investigated real three-dimensional (3D) objects with regard to performance on a mental rotation task and whether the appearance of sex differences may be mediated by experiences with spatially related activities. 40 men and 40 women were presented with alternating timed trials consisting of real-3D objects or two-dimensional illustrations of 3D objects. Sex differences in spatially related activities did not significantly influence the finding that men outperformed women on mental rotation of either stimulus type. However, on measures related to spatial activities, self-reported proficiency using maps correlated positively with performance only on trials with illustrations whereas self-reported proficiency using GPS correlated negatively with performance regardless of stimulus dimensionality. Findings may be interpreted as suggesting that rotating real-3D objects utilizes distinct but overlapping spatial skills compared to rotating two-dimensional representations of 3D objects, and real-3D objects can enhance mental rotation performance.