Expression influences the recognition of familiar faces

Face recognition has been assumed to be independent of facial expression. We used familiar and unfamiliar faces that were morphed from a happy to an angry expression within a given identity. Participants performed speeded two-choice decisions according to whether or not a face was familiar. Consistent with earlier findings, reaction times for classifications of unfamiliar faces were independent of facial expressions. In contrast, expression clearly influenced the recognition of familiar faces. with fastest recognition for moderately happy expressions. This suggests that representations of familiar faces for recognition preserve some information about typical emotional expressions.     

Distance estimation in a dynamic simulated environment: a visual field dependence problem?

Egocentric distance estimation implies that the subject perceives his own location in the environment. In a simulated environment, subjects have to transpose perceptively their own observation point in order to assume their virtual body position. As only visual information specifies this position, their ability to perceive the camera viewpoint should be linked to the field dependence independence factor (FDI). Field-independent subjects underestimated the mid-distance between their own virtual body position and a far-located target; their bisection was located between the projective (2-D) and the simulated (3-D) mid-distance which indicates their difficulty in considering the in-depth simulated spatial references. High correlations between the vertical estimation in the rod-and-frame test and the egocentric-distance-estimation task (with shifted camera) suggest a similar perceptive process in both tasks. This result is confirmed by the better performances of the field-dependent subjects in this condition. In conclusion, we discuss the relationship between FDI and the sense of presence in virtual environments.     

Actions blind to conceptually overlapping stimuli

Participants are worse at identifying spatial symbols (arrowheads) while performing spatially compatible manual key presses. The present experiments investigated the generality of this blindness effect to response-compatible stimuli. In Experiment 1 a left key press deteriorated the identification of left-pointing arrows, and a right key press deteriorated the perception of right-pointing arrows, independent of the hands used to press the key. Thus the blindness effect is based on codes of the distal response location rather than on the body-intrinsic anatomical connection of the hands. Experiment 2 extended the blindness effect to verbal responses and written position words (left, right, up, down). Vocalizing a position word blinded to directly compatible position words (e.g., left-left), but not to orthogonally compatible position words (e.g., left-down). This result suggests that the use of identical stimulus-response codes, and not the use of saliency-matching but distinct codes, suffices to produce blindness effects. Finally, Experiment 3 extended the blindness phenomenon beyond the spatial domain by demonstrating blindness between saying color words and perceiving color patches. Altogether, the experiments revealed action-induced blindness to be a phenomenon of broad empirical validity occurring whenever action and perception afford simultaneous access to the same conceptual codes.     

Perceiving action identity: how pianists recognize their own performances

Can skilled performers, such as artists or athletes, recognize the products of their own actions? We recorded 12 pianists playing 12 mostly unfamiliar musical excerpts, half of them on a silent keyboard. Several months later, we played these performances back and asked the pianists to use a 5-point scale to rate whether they thought they were the person playing each excerpt (1 = no, 5 = yes). They gave their own performances significantly higher ratings than any other pianist's performances. In two later follow-up tests, we presented edited performances from which differences in tempo, overall dynamic (i.e., intensity) level, and dynamic nuances had been removed. The pianists' ratings did not change significantly, which suggests that the remaining information (expressive timing and articulation) was sufficient for self-recognition. Absence of sound during recording had no significant effect. These results are best explained by the hypothesis that an observer's action system is most strongly activated during perception of self-produced actions.     

The closer we are,the more we are alike: The effect of self-other merging on depersonalized self-perception

The present study examined whether or not the extent to which people include other group members in the self, influences depersonalized self-perception (i.e., perceiving self and others as similar in terms of group characteristics). The results revealed that self-other merging positively influenced feelings of belongingness and identification with the in-group. Furthermore, a strong experience of self-other merging was shown to lead to depersonalized self-perception as measured by a self-assimilation and an in-group homogeneity index. Finally, results also revealed that feelings of belongingness and group identification mediated, at least partly, the effect of self-other merging on depersonalized self-perception. The findings are discussed in light of the literature on self-expansion.     

A new estimation of the duration of attentional dwell time

How rapidly can attention move from one object to the next? Previous studies in which the dwell time paradigm was used have estimated attentional switch times of 200–500 msec, results incompatible with the search rate estimates of 25–50 msec shown in numerous visual search studies. It has been argued that dwell times are so long in the dwell time paradigm because the attentional shifts measured are unlike those used in visual search. In the present experiment, a variation of a visual search task was used, in which serial endogenous (volitional) deployments of attention were measured directly by means of a probe reaction time task. The experiment revealed a dwell time of about 250 msec, consistent with the faster estimates from other dwell time studies. This result suggests that endogenous shifts of attention may be relatively slow and that the faster attentional shifts estimated from visual search tasks may be due to the involvement of bottom-up processes.     

Sensorimotor simulations underlie conceptual representations: Modality-specific effects of prior activation

According to the perceptual symbols theory (Barsalou, 1999), sensorimotor simulations underlie the representation of concepts. Simulations are componential in the sense that they vary with the context in which the concept is presented. In the present study, we investigated whether representations are affected by recent experiences with a concept. Concept names (e.g., APPLE) were presented twice in a property verification task with a different property on each occasion. The two properties were either from the same perceptual modality (e.g.,green, shiny) or from different modalities (e.g.,tart, shiny). All stimuli were words. There was a lag of several intervening trials between the first and second presentation. Verification times and error rates for the second presentation of the concept were higher if the properties were from different modalities than if they were from the same modality.     

Effects of redundant visual stimuli on temporal order judgments

Four experiments were conducted in order to compare the effects of stimulus redundancy on temporal order judgments (TOJs) and reaction times (RTs). In Experiments 1 and 2, participants were presented in each trial with a tone and either a single visual stimulus or two redundant visual stimuli. They were asked to judge whether the tone or the visual display was presented first. Judgments of the relative onset times of the visual and the auditory stimuli were virtually unaffected by the presentation of redundant, rather than single, visual stimuli. Experiments 3 and 4 used simple RT tasks with the same stimuli, and responses were much faster to redundant than to single visual stimuli. It appears that the traditional speedup of RT associated with redundant visual stimuli arises after the stimulus detection processes to which TOJs are sensitive.     

Seriality of phonological encoding in naming objects and reading their names

There is a remarkable lack of research bringing together the literatures on oral reading and speaking. As concerns phonological encoding, both models of reading and speaking assume a process of segmental spellout for words, which is followed by serial prosodification in models of speaking (e.g., Levelt, Roelofs, & Meyer, 1999). Thus, a natural place to merge models of reading and speaking would be at the level of segmental spellout. This view predicts similar seriality effects in reading and object naming. Experiment 1 showed that the seriality of encoding inside a syllable revealed in previous studies of speaking is observed for both naming objects and reading their names. Experiment 2 showed that both object naming and reading exhibit the seriality of the encoding of successive syllables previously observed for speaking. Experiment 3 showed that the seriality is also observed when object naming and reading trials are mixed rather than tested separately, as in the first two experiments. These results suggest that a serial phonological encoding mechanism is shared between naming objects and reading their names.     

Update Semantics of Security Protocols

We present a model-theoretic approach for reasoning about security protocols, applying recent insights from dynamic epistemic logics. This enables us to describe exactly the subsequent epistemic states of the agents participating in the protocol, using Kripke models and transitions between these based on updates of the agents’ beliefs associated with steps in the protocol. As a case study we will consider the SRA Three Pass protocol and discuss the Wide-Mouthed Frog protocol.