Is conscious perception gradual or dichotomous? A comparison of report methodologies during a visual task

In a recent article, [Sergent, C. &; Dehaene, S. (2004). Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink, Psychological Science, 15(11), 720–729] claim to give experimental support to the thesis that there is a clear transition between conscious and unconscious perception. This idea is opposed to theoretical arguments that we should think of conscious perception as a continuum of clarity, with e.g., fringe conscious states [Mangan, B. (2001). Sensation’s ghost—the non-sensory “fringe” of consciousness, Psyche, 7, 18]. In the experimental study described in this article, we find support for this opposite notion that we should have a parsimonious account of conscious perception. Our reported finding relates to the hypothesis that there is more than one perceptual threshold [Merikle, P.M., Smilek, D. &; Eastwood, J.D. (2001). Perception without awareness: perspectives from cognitive psychology, Cognition, 79, 115–134], but goes further to argue that there are different “levels” of conscious perception.     

Procedural memory in dissociative identity disorder: when can inter-identity amnesia be truly established?

In a serial reaction time task, procedural memory was examined in Dissociative Identity Disorder (DID). Thirty-one DID patients were tested for inter-identity transfer of procedural learning and their memory performance was compared with 25 normal controls and 25 controls instructed to simulate DID. Results of patients seemed to indicate a pattern of inter-identity amnesia. Simulators, however, were able to mimic a pattern of inter-identity amnesia, rendering the results of patients impossible to interpret as either a pattern of amnesia or a pattern of simulation. It is argued that studies not including DID-simulators or simulation-free memory tasks, should not be taken as evidence for (or against) amnesia in DID.     

Uncovering the problem-solving process: cued retrospective reporting versus concurrent and retrospective reporting

This study investigated the amounts of problem-solving process information ("action," "why," "how," and "metacognitive") elicited by means of concurrent, retrospective, and cued retrospective reporting. In a within-participants design, 26 participants completed electrical circuit troubleshooting tasks under different reporting conditions. The method of cued retrospective reporting used the original computer-based task and a superimposed record of the participant's eye fixations and mouse-keyboard operations as a cue for retrospection. Cued retrospective reporting (with the exception of why information) and concurrent reporting (with the exception of metacognitive information) resulted in a higher number of codes on the different types of information than did retrospective reporting.     

Preference for spatial cues in a non-storing songbird species

Male mammals typically outperform their conspecific females on spatial tasks. A sex difference in cues used to solve the task could underlie this performance difference as spatial ability is reliant on appropriate cue use. Although comparative studies of memory in food-storing and non-storing birds have examined species differences in cue preference, few studies have investigated differences in cue use within a species. In this study, we used a one-trial associative food-finding task to test for sex differences in cue use in the great tit, Parus major. Birds were trained to locate a food reward hidden in a well covered by a coloured cloth. To determine whether the colour of the cloth or the location of the well was learned during training, the birds were presented with three wells in the test phase: one in the original location, but covered by a cloth of a novel colour, a second in a new location covered with the original cloth and a third in a new location covered by a differently coloured cloth. Both sexes preferentially visited the well in the training location rather than either alternative. As great tits prefer colour cues over spatial cues in one-trial associative conditioning tasks, cue preference appears to be related to the task type rather than being species dependent.     

The heterogeneity of picture-supported narratives in Alzheimer's disease

This study describes discourse patterns produced by 46 Alzheimer disease (AD) patients and 53 normal elderly subjects in two picture-supported narratives. Nine measures derived from a cognitive model of discourse processing were obtained and submitted to cluster analysis. Results indicate that discourse patterns elicited from both stimuli were heterogeneous. Further, they fail to clearly differentiate between normal aging and AD in half of the AD patients. Discourse patterns are examined in light of various sources of heterogeneity including severity of cognitive impairment, subject characteristics, and task demands. The usefulness of discourse as a diagnostic and therapeutic tool is discussed.     

What determines the eyes' landing position in words?

The place at which the eyes first fixate in a word during continuous reading, called the preferred landing position (PLP), is usually located halfway between the beginning and the middle of the word. To propose a mechanism that might account for the off-center location of the PLP, six eye movement experiments were conducted using a lexical decision task (Experiment 1) and a stimulus bisection task (Experiments 2-6). The type of stimulus--linguistic (words and nonwords) versus nonlinguistic (strings of hashes, dotted lines, and solid lines)--and the stimulus presentation side (left vs. right) were manipulated. The results showed that (1) stimulus discreteness versus continuousness is an important factor in saccade computation and (2) PLP asymmetry can be explained in terms of attentional and/or oculomotor processes.     

Auditory ERP in extremely premature 5-year-old children

The aim of this research was to test the hypothesis of a functional impairment in the automatic detection of deviant tones in 141 children born after 25 to 28 weeks of gestational age, as compared to 45 age-matched full-term control children. All of them were assessed at age 5 years 9 months and instructed to listen passively to two different pure tones (1000 vs 1200 Hz; 20 vs 80%) counterbalanced between ears. Rarity was thus defined by specific ear by tone combinations. The temporal N100 showed a clear contralateral functional organization of the central auditory pathway, especially for the left ear, but without group difference. By contrast, in full-term controls but not in premature children, the central N200 was specifically increased over frontal leads to rare stimuli as compared to frequent. Premature children demonstrated a lack of brain response when more complex processing integrating different informations was required.     

Is surface dysgraphia tied to semantic impairment? Evidence from a case of semantic dementia

Recent models of lexical processing suggest that written spelling partly depends upon the semantic system. According to these models, a deterioration in word meanings would necessarily lead to a spelling impairment, especially for low-frequency and orthographically irregular words. We report a case study of a patient (MK) with semantic dementia who presents impairments in knowledge of word meanings and surface dysgraphia. By specifically identifying concepts that are still known or that are partially or completely deteriorated, we show that the patient's spelling deficit is highly correlated with word comprehension. These data confirm that surface dysgraphia is directly linked to the breakdown in semantic memory.     

Involvement of short-term memory in complex mental calculation

The aim of this study was to examine the involvement of the short-term memory system in complex mental addition by manipulating the phonological and visual similarity of two numbers to be added. The phonological similarity of the problems appeared to have a major effect on both speed and accuracy. However, the manipulation of visual similarity failed to have any measurable impact. This suggests that the phonological loop, rather than the visual-spatial sketch pad, would be used preferably for temporary storage of addends. An interpretation of these results in terms of the nature of the internal code underlying this task is discussed.     

Detecting anticipatory events in handwriting movements

We investigated how visual processes exploit specific anticipatory movements observed in handwriting gestures. Previous research has shown that the kinematic information contained in the downstroke of an l is exploited to predict the identity of the forthcoming letter. Here, we determined the moment at which prediction takes place. Two between-letter effects were examined: changes in size (ll vs le) and changes in rotation direction (le vs ln). Results show that with only 75% of the l downstroke trajectory (or 60% of the downstroke time) subjects are already capable of predicting the identity of the letter following the l, that is well before the end of the downstroke. Analysis also reveals that identification takes place after the presentation of the movement acceleration phase. The visual perception of motor anticipation seems to involve the detection of motor events.