The wisdom of crowds in one mind: How individuals can simulate the knowledge of diverse societies to reach better decisions

The joint knowledge of many diverse individuals can outperform experts in estimation and decision-making problems. This wisdom of the crowd has been demonstrated in different societal areas such as internet search engines, political elections or stock markets. Recently, psychologists argued that humans may even simulate a diverse society in their own minds by drawing different answers from their brain (Vul &; Pashler, 2008). The underlying idea is that individuals can access different knowledge areas in their brain, whose joint evaluation yields better estimates than their separate consideration. This article presents a mathematical treatment of the wisdom of crowds and two potential mechanisms to quantify the wisdom of crowds in one mind. The implications of both methods are analyzed and applied to new experimental data (N=144), which contain five consecutive estimates from the same individuals. The theoretical and empirical analysis demonstrates limitations of the wisdom of crowds in one mind: Asking oneself several times is on average less powerful than asking only one other individual. This is due to the smaller diversity of estimates of similar individuals and the larger average bias to which they converge. Further, individuals cannot perform independent draws from an “internal distribution”. Hence, there may be other mechanisms at work such as talking oneself into believing initial guesses or eliciting progressively wilder ones.     

Unconscious activation of task sets

Using an explicit task cuing paradigm, we tested whether masked cues can trigger task-set activation, which would suggest that unconsciously presented stimuli can impact cognitive control processes. Based on a critical assessment of previous findings on the priming of task-set activation, we present two experiments with a new method to approach this subject. Instead of using a prime, we varied the visibility of the cue. These cues either directly signaled particular tasks in Experiment 1, or certain task transitions (i.e., task repetitions or switches) in Experiment 2. While both masked task and transition cues affected task choice, only task cues affected the speed of task performance. This observation suggests that task-specific stimulus–response rules can be activated only by masked cues that are uniquely associated with a particular task. Taken together, these results demonstrate that unconsciously presented stimuli have the power to activate corresponding task sets.     

Temporal-range estimation of multiple objects: evidence for an early bottleneck

When making parallel time-to-contact (TTC) estimates of two approaching objects, the two respective TTC estimates interfere with one another in an asymmetric fashion. The TTC of the later-arriving object is systematically overestimated, while the estimated TTC for the first-arriving object is as accurate as in a condition presenting only a single object. This asymmetric interference points to a processing bottleneck that could be due to early (e.g., during the estimation of the TTC from the optic flow) or late (e.g., during the timing of the response or the motor execution) constraints in the TTC estimation process. We used a Sperling-like prediction-motion task to differentiate between these two possibilities. Participants produced an absolute estimate of the TTC of only one of two objects approaching a target line. The target object to which the response was to be made was indicated by an auditory cue that occurred either at motion-onset or at the instant at which the two objects disappeared from the screen (occlusion-onset). The cue at motion-onset should disengage visual processing of the irrelevant stimulus. The cue at occlusion-onset, in contrast, requires visual processing of both relevant and irrelevant stimulus until occlusion. A single-object condition was introduced as a control condition. Results show symmetric interference in the motion-onset condition. In the occlusion-onset condition however, the results were congruent with asymmetric interference. Thus, the processing bottleneck in TTC estimation is originating at the earlier stages.     

Heuristics and invariants in dynamic event perception: Immunized concepts or nonstatements?

There is ample evidence showing that observers are able to judge dynamic properties of moving objects on the basis of visual kinematics. It is, however, widely disputed as to how to explain this body of data. While direct perceptionists claim that observers have direct access to the underlying dynamics of the event (kinematic specification of dynamics, or KSD, principle), contenders of the perceptual heuristics approach (PH) suggest that observers use the visual equivalent of a heuristic to arrive at their judgments about dynamics. First, the critical assumptions of the KSD principle are discussed in order to motivate the claim that the KSD principle cannot be falsified and is thus immune to empirical criticism. Then the same scrutiny is applied to the PH approach. It is, in its general form at least, afflicted with a similar lack of falsifiability. In comparing the concepts underlying invariants and perceptual heuristics, my conclusion is that a critical experiment aimed at deciding between the two approaches is impossible, and that KSD and PH can be regarded as nonstatements. The findings reported in the event-perception literature must therefore be reevaluated on these grounds.     

Time-to-passage judgments in nonconstant optical flow fields

The time until an approaching object will pass an observer (time to passage, or TTP) is optically specified by a global flow field even in the absence of local expansion or size cues. Kaiser and Mowafy (1993) have demonstrated that observers are in fact sensitive to this global flow information. The present studies investigate two factors that are usually ignored in work related to TTP: (1) non-constant motion functions and (2) concomitant eye rotation. Non-constant velocities violate an assumption of some TTP derivations, and eye rotations may complicate heading extraction. Such factors have practical significance, for example, in the case of a pilot accelerating an aircraft or executing a roll. In our studies, a flow field of constant-sized stars was presented monocularly on a large screen. TTP judgments had to be made on the basis of one target star. The flow field varied in its acceleration pattern and its roll component. Observers did not appear to utilize acceleration information. In particular, TTPs with decelerating motion were consistently underestimated. TTP judgments were fairly robust with respect to roll, even when roll axis and track vector were decoupled. However, substantial decoupling between heading and track vector led to a decrement in performance, in both the presence and the absence of roll.     

Retinal,attentional, and causal aspects of illusory-motion directionality

Extended objects presented instantaneously appeared to propagate or grow into their final shape. A strong bias was found toward perceiving straight lines to grow away from the observer's point of fixation. If attention and fixation were not directed to the same point of the visual field, both influenced illusory motion directionality, and if another small object was present on the screen at a location that was neither fixated nor attended to, the object that was instantaneously presented seemed to grow away from this point. Thus, three factors are involved in illusory-motion directionality: biases toward perceiving objects spreading away from the fixation point, away from an attended area, and away from preexisting objects. The experiments indicate that a satisfactory explanation of the illusion has to include bottom-up and top-down processes. They also challenge existing theories of motion detection.     

Lösungsstrategien beim Attneaveschen Rateversuch

Zusammenfassung Der Rateversuch von Attneave wurde durch Zulassung freier Ratestrategien modifiziert und der Lösungsvorgang der Rateaufgabe zum Thema einer Untersuchung gemacht. Es zeigte sich, daß die Rateleistung (Position des letzten Fehlers) mit zwei provisorisch gebildeten Strategiemerkmalen kovariiert: der Systematik der Abfolge und dem Verhalten nach einem Fehler. Je weniger systematisch die Reihenfolge überprüfter Flächenelemente ist oder/und je konsequenter die positive Strategie der Suche nach dem Figurverlauf auch nach der Widerlegung von Teilhypothesen beibehalten wird, um so besser ist die Rateleistung. Die Befunde werden kurz diskutiert.     

Acquiring a Taste: Alcohol Experiences of German Elementary School Children

Few data are available on alcohol experiences among elementary school children, although early onset and trying of alcohol use is known to be a risk factor for adolescent alcohol abuse. Until now, research leaves open the question on which factors encourage early trying behavior. In a cross-sectional study design, a written survey was conducted in 49 randomly selected elementary schools in Germany. The survey was carried out among 3rd and 4th graders with a median age of 9 years during class time in the school year 2010/2011. 1806 questionnaires were included in the study. The risk behavior of having tried alcohol was analyzed. A total of 37.7% (n = 681) of all children reported to have already tried alcohol. While grade and age had no significant influence in the final multivariate model, the gender effect stayed relevant (Male: aOR 1.2, 95%-CI 1.0–1.5), as did the question of whether the child liked going to school (No: aOR 1.4, 95%-CI 1.1–1.7), a lack of parental monitoring (aOR 1.5, 95%-CI 1.1–2.1), consistent parenting (Sometimes/never: aOR 1.5, 95%-CI 1.1–1.9), a regularly provided break-time snack (No: aOR 2.2, 95%-CI 1.3–3.8), as well as parents’ drinking (Yes: aOR 2.0, 95%-CI 1.6–2.6) and drinking among peers (Yes: aOR 8.5, 95%-CI 6.2–11.6). Our study shows that alcohol experiences can be highly prevalent among 3rd and 4th grade elementary school children in Germany. Our findings suggest that especially those variables which may be controlled by the parents are strongly associated with children’s alcohol experiences suggesting a starting point for preventative intervention measures. The results also indicate the need for innovative gender-sensitive approaches in the living environment of elementary school children.     

Measuring perceived ceiling height in a visual comparison task

When judging interior space, a dark ceiling is judged to be lower than a light ceiling. The method of metric judgments (e.g., on a centimetre scale) that has typically been used in such tasks may reflect a genuine perceptual effect or it may reflect a cognitively mediated impression. We employed a height-matching method in which perceived ceiling height had to be matched with an adjustable pillar, thus obtaining psychometric functions that allowed for an estimation of the point of subjective equality (PSE) and the difference limen (DL). The height-matching method developed in this paper allows for a direct visual match and does not require metric judgment. It has the added advantage of providing superior precision. Experiment 1 used ceiling heights between 2.90?m and 3.00?m. The PSE proved sensitive to slight changes in perceived ceiling height. The DL was about 3% of the physical ceiling height. Experiment 2 found similar results for lower (2.30?m to 2.50?m) and higher (3.30?m to 3.50?m) ceilings. In Experiment 3, we additionally varied ceiling lightness (light grey vs. dark grey). The height matches showed that the light ceiling appeared significantly higher than the darker ceiling. We therefore attribute the influence of ceiling lightness on perceived ceiling height to a direct perceptual rather than a cognitive effect.     

Expanding motivations for global justice: A dialogue between public Christian social ethics and Ubuntu ethics as Afro-communitarianism

Faced with the ongoing tragedy of poverty, ethicists call for effective measures of global justice to set up just institutional structures. Their arguments for a transnational obligation to help however remain contested, one of the main reasons for that being the lack of motivational support for trans-national visions of global justice. This articles suggests that the debate will gain new and helpful insights if it studies the motivational mechanisms at work in the dominant religious and cultural traditions, asking: How do these particular traditions conceive of social justice; how do they motivate their adherents to extend solidarity? And how can the similarities surfacing in their motivational strategies be informative for the quest to devise a motivationally saturated account of global justice? The article demonstrates the potential of such an concrete-universal discourse in an exemplary manner by staging a dialogue between public Christian Social Ethics and African Ubuntu Ethics.