Effects of outcome and trial frequency on the inverse base-rate effect

The inverse base-rate effect is a bias in contingency learning in which participants tend to predict a rare outcome for a conflicting set of perfectly predictive cues. Although the effect is often explained by attention biases during learning, inferential strategies at test may also contribute substantially to the effect. In three experiments, we manipulated the frequencies of outcomes and trial types to determine the critical conditions for the effect, thereby providing novel tests of the reasoning processes that could contribute to it. The rare bias was substantially reduced when the outcomes were experienced at equal rates in the presence of predictive-cue frequency differences (Exp. 2), and when the predictive cues were experienced at equal rates in the presence of outcome frequency differences (Exp. 3). We also found a consistent common-outcome bias for novel cue compounds. The results indicate the importance of both cue and outcome frequencies to the inverse base-rate effect, and reveal a combination of necessary conditions that are not well captured by appealing to inferential strategies at test. Although both attention-based and inferential theories explain some aspects of these data, no existing theory fully accounts for these effects of relative novelty.     

Can confidence come too soon? Collective efficacy,conflict and group performance over time

Groups with a strong sense of collective efficacy set more challenging goals, persist in the face of difficulty, and are ultimately more likely to succeed than groups who do not share this belief. Given the many advantages that may accrue to groups who are confident, it would be logical to advise groups to build a high level of collective efficacy as early as possible. However, we draw on Whyte’s (1998) theory of collective efficacy and groupthink, to predict that when confidence emerges at a high level toward the beginning of a group’s existence, group members may be less likely to engage in process conflict; a form of conflict that may be beneficial in the early phase of a group project. We found support for this prediction in two longitudinal studies of classroom project teams.     

Rapid learning of rapid temporal contexts

In an information-rich visual world and with limited attentional resources, what visual cues allow humans to efficiently navigate their environment? One key environmental characteristic is that stimuli rarely appear in isolation and typically coincide with other specific items that provide cues regarding where and when to guide our attention. Indeed, a predictive spatial context of distractors can enhance the deployment of attention to a target location (Chun &; Jiang, 1998). However, can a predictive, temporal sequence of distractors, which do not enter working memory, cue when to allocate attention? Previous studies addressing this question have employed relatively long (?500 msec/item) stimulus exposure durations. Thus, this temporal cuing may require extensive processing of the distractors. Here, we show that a rapidly presented (～100 msec/item), predictive, temporal context, where stimuli undergo only preliminary analysis, can facilitate the deployment of attention to a specific temporal location.     

On the Nature of Cognitive Control and Endogenous Orienting: A Response to Chica and Bartolomeo (2010)

Chica and Bartolemeo (Unconscious strategies? Commentary on Risko and Stolz (2010): The proportion valid effect in covert orienting: Strategic control or implicit learning? Consciousness and Cognition, 19, 443–444.) agree that our results (Risko, E. F., & Stolz, J. A. (2010). The proportion valid effect in covert orienting: Strategic control or implicit learning? Consciousness and Cognition, 19, 432–442.) are consistent with an implicit learning account of the proportion valid effect. Nevertheless, they raise two general issues (1) that an explicit strategy might be operative in other contexts and (2) that orienting in response to implicit knowledge is endogenous. In our response, we address each of these issues and further discuss the concepts of endogenous orienting and cognitive control.     

Interference resolution in major depression

In two experiments, we investigated individual differences in the ability to resolve interference in participants diagnosed with major depressive disorder (MDD). Participants were administered the “Ignore/Suppress” task, a short-term memory task composed of two steps. In Step 1 (“ignore”), participants were instructed to memorize a set of stimuli while ignoring simultaneously presented irrelevant material. In Step 2 (“suppress”), participants were instructed to forget a subset of the previously memorized material. The ability to resolve interference was indexed by response latencies on two recognition tasks in which participants decided whether a probe was a member of the target set. In Step 1, we compared response latencies to probes from the to-be-ignored list with response latencies to nonrecently presented items. In Step 2, we compared response latencies to probes from the to-be-suppressed list with response latencies to nonrecently presented items. The results indicate that, compared with control participants, depressed participants exhibited increased interference in the “suppress” but not in the “ignore” step of the task, when the stimuli were negative words. No group differences were obtained when we presented letters instead of emotional words. These findings indicate that depression is associated with difficulty in removing irrelevant negative material from short-term memory.     

Dissociable interference-control processes in perception and memory

Control over interference is a pervasive feature of cognitive life. Central to research on interference control has been the identification of its underlying mechanisms. Investigations have focused on processes that filter out distracting perceptual information, leading to negative priming, and processes that discard intruding memories that cause proactive interference. Theories differ regarding whether or not a single process during episodic retrieval underlies both negative priming and the resolution of proactive interference. Using functional magnetic resonance imaging, we combined both phenomena into a single paradigm and found that occipital cortex shows activation uniquely related to negative priming, whereas activation increases in left lateral prefrontal cortex are uniquely associated with proactive interference. This pattern of results contradicts theories that rely on a single process to account for both phenomena. However, results also showed common recruitment of right dorsolateral prefrontal cortex and parietal regions and therefore suggest that some control processes are shared.