Beta-MPT: Multinomial processing tree models for addressing individual differences

Traditionally, multinomial processing tree (MPT) models are applied to groups of homogeneous participants, where all participants within a group are assumed to have identical MPT model parameter values. This assumption is unreasonable when MPT models are used for clinical assessment, and it often may be suspect for applications to ordinary psychological experiments. One method for dealing with parameter variability is to incorporate random effects assumptions into a model. This is achieved by assuming that participants’ parameters are drawn independently from some specified multivariate hyperdistribution. In this paper we explore the assumption that the hyperdistribution consists of independent beta distributions, one for each MPT model parameter. These beta-MPT models are ‘hierarchical models’, and their statistical inference is different from the usual approaches based on data aggregated over participants. The paper provides both classical (frequentist) and hierarchical Bayesian approaches to statistical inference for beta-MPT models. In simple cases the likelihood function can be obtained analytically; however, for more complex cases, Markov Chain Monte Carlo algorithms are constructed to assist both approaches to inference. Examples based on clinical assessment studies are provided to demonstrate the advantages of hierarchical MPT models over aggregate analysis in the presence of individual differences.     

Implicit learning of social predictions

Humans exchange a range of nonverbal social signals in every interaction. It is an open question whether people use these signals, consciously or unconsciously, to guide social behavior. This experiment directly tested whether participants could learn to predict another person’s behavior using nonverbal cues in a single interaction, and whether explicit knowledge of the cue-outcome relationship was necessary for successful prediction. Participants played a computerized game of rock-paper-scissors against an avatar they believed was another participant. Sometimes the avatar generated a predictive facial cue before the play. On these trials, participants’ win-frequency increased over time, even if they did not acquire explicit knowledge of the predictive cue. The degree to which participants could predict the avatar (wins on cued trials) related to their self-reported liking of the avatar. These findings demonstrate the importance of implicit associative learning mechanisms in guiding social behavior on a moment-to-moment basis during interaction.     

Count out your intrusions: Effects of verbal encoding on intrusive memories

Peri-traumatic information processing is thought to affect the development of intrusive trauma memories. This study aimed to replicate and improve the study by Holmes, Brewin, and Hennessy (2004, Exp. 3) on the role of peri-traumatic verbal processing in analogue traumatic intrusion development. Participants viewed an aversive film under one of three conditions: counting backwards in 3s (“verbal interference”), verbalising emotions and thoughts (“verbal enhancement”), or without an extra task. A dual-process account of PTSD would predict that verbal interference would increase intrusion frequency compared to no task, whereas verbal enhancement would lead to a decrease. In contrast, mainstream memory theory predicts a decrease in intrusion frequency from any concurrent task that diverts attention away from the trauma film. The main finding was that the verbal interference task led to a decrease in intrusive memories of the film compared to the other two conditions. This finding does not support a dual-process account of PTSD, but is in line with general theories of memory and attention.     

The kinds of information that support novel associative object priming and how these differ from those that support item priming

We investigated how the information that supports novel associative and item object priming differs under identical study/test conditions. In Experiments 1 and 2, participants rated the meaningfulness of sentences linking two object pictures at study. At test, they performed either a size judgement or an associative recognition memory task on intact, recombined and novel picture (Experiment 1) or word (Experiment 2) associations. Associative priming was modulated by subjective meaningfulness of the encoded links, and depended on study/test perceptual overlap. In contrast, item priming was neither affected by the meaningfulness of the sentences nor by study/test changes in the stimulus presentation format. Associative priming and recognition were behaviourally dissociated, and associative recognition was probably too slow to have seriously contaminated associative priming. In Experiment 3, participants performed a perceptually oriented task during both experimental phases, and both associative and item priming were observed. These results suggest that associative priming depends on stored associative semantic and perceptual information when the test task requires flexible retrieval of associative information. Under the same conditions, item priming may only require activation of items' semantic properties. When both study and test tasks stress perceptual processing, retrieval of perceptual information is sufficient to support both kinds of priming.     

Does survival context enhance memory for source? A within-subjects comparison

ABSTRACT

Nairne, Thompson, and Pandeirada [2007. Adaptive memory: Survival processing enhances retention. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 263–273] demonstrated that processing words according to their relevance to a survival scenario enhanced their subsequent retrieval in recall and recognition tasks compared to a variety of control scenarios. From an adaptive perspective, it is maintained that processing words in a survival context should also enhance memory for source; however, evidence in the literature is rather mixed regarding a survival context advantage for source memory. In the current study, we conducted four experiments to systematically investigate the survival advantage in source memory, when the context itself is the source, with both recall (Experiments 1A and 1B) and recognition tests (Experiments 2A and 2B). Results showed a survival advantage for item memory over the control contexts in all experiments. The survival context advantage was not extended to source memory performance in Experiment 1A. Results from all other experiments, however, indicated a survival context advantage for both item and source memory. Findings are discussed in relation to possible proximate mechanisms underlying the survival processing effect.     

Effects of survival processing and retention interval on true and false recognition in the DRM and category repetition paradigms

ABSTRACT

Two experiments examined the effects of survival processing and delay on true and related false recognition. Experiment 1 used the Deese-Roediger-McDermott paradigm and found survival processing to increase true and related false recognition. Extending the delay from 5-mins to 1-day reduced true, but not false memory. Measures of the characteristics of true and false memories showed survival processing increased “remember” and “know” responses for related false memory, “know” responses for true memory and gist processing. Experiment 2 made use of the category repetition procedure and found a broadly similar pattern of results for true memory. However, related false memory was decreased by survival processing. Except for one result, no interactions were found between encoding task and delay. Overall, survival processing produced similar or different effects on true/false memory depending on the nature of the list. The mechanisms that might underpin these are evaluated and considered in relation to future work.     

Adapting to test structure: Letting testing teach what to learn

We propose that we encode and store information as a function of the particular ways we have used similar information in the past. More specifically, we contend that the experience of retrieval can serve as a powerful cue to the most effective ways to encode similar information in comparable future learning episodes. To explore these ideas, we did two studies in which all participants went through study–test cycles of single category lists while we manipulated the nature of the recognition tests. The recognition tests either included only same-category lures or only different-category lures. The experience of repeated testing leads participants to avoid conceptual-based strategies but only when conceptual knowledge was poorly diagnostic for recognition (i.e., in the same-category lures condition). In a second study with a similar manipulation, we showed that repeated testing with lures from the same category as study items improved performance in a final recall surprise test compared to conditions in which different-category lures were used. Such a difference is akin to the one obtained when encoding instructions focus on distinctive item features compared to cases in which the focus is on relational processing. We suggest that testing requirements lead to adaptive changes at encoding.     

观察者公正敏感性对不公正信息加工的影响

为考查观察者公正敏感性对不公正信息加工（注意、解释）的影响,该研究开展了两个实验研究。在实验一中,让被试观看不公正影片剪辑或中性剪辑后,要求他们完成视觉探测任务,判断探测刺激是在不公正词汇还是中性词汇的左边或右边;在实验二中,让被试对一个模糊的暗含不公正意义的影片剪辑中的主角进行公正性评价。结果表明,当被试不公正概念被激活后,观察者公正敏感性高的被试比观察者公正敏感性低的被试对不公正信息的注意加工更集中和更自动,同时他们对模糊的信息解释为更不公正。     

Implicit volition and stereotype control

Goals are mental representations that vary in accessibility and operate within goal systems. The implicit nature of goal activation and pursuit is shown here to make goals effective not merely at overturning the influence of an activated stereotype on how people respond to members of stereotyped groups, but effective at implicitly controlling the activation of stereotypes in the first place. In a set of experiments examining chronic egalitarian goals, faces and names of members of stereotyped groups presented as target stimuli led to the inhibition of stereotypes, as well as to the heightened accessibility of egalitarian goals. A separate set of experiments illustrate a similar ability of individuals to control stereotype activation when egalitarian goals are temporarily triggered within a context, rather than being chronically held. Goals that require one to inhibit stereotypic associations to a target can lead to the intended, yet implicit, control of stereotype activation, even when one is not aware the goal is active or being pursued or being regulated.     

Putting yourself in the skin of a black avatar reduces implicit racial bias

Although it has been shown that immersive virtual reality (IVR) can be used to induce illusions of ownership over a virtual body (VB), information on whether this changes implicit interpersonal attitudes is meager. Here we demonstrate that embodiment of light-skinned participants in a dark-skinned VB significantly reduced implicit racial bias against dark-skinned people, in contrast to embodiment in light-skinned, purple-skinned or with no VB. 60 females participated in this between-groups experiment, with a VB substituting their own, with full-body visuomotor synchrony, reflected also in a virtual mirror. A racial Implicit Association Test (IAT) was administered at least three days prior to the experiment, and immediately after the IVR exposure. The change from pre- to post-experience IAT scores suggests that the dark-skinned embodied condition decreased implicit racial bias more than the other conditions. Thus, embodiment may change negative interpersonal attitudes and thus represent a powerful tool for exploring such fundamental psychological and societal phenomena.