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Results for “Signal Detection, Psychological”

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At least 55 records · Page 3Linked to original sources

PubMed2000

When complexity helps: an electrophysiological analysis of multiple feature benefits in object perception.

Fournier, L. R., Eriksen, C. W. and Bowd, C. (1998. Multiple feature discrimination faster than single feature discrimination within the same object? Perception & Psychophysics 60, 1384-1405) found that judging the presence of multiple features within an object is faster than judging the presence of the least discriminable of these features alone (multiple feature benefits, MFBs). When an 'absent' response is required, responses are slower when some of the relevant (target) features are present (multiple feature costs, MFCs). The present study utilized psychophysiological measures (of the event-related brain potential and the electromyogram) to determine the contributions of response priming and stimulus evaluation processes (P300 latency) to these effects. P300 latency and reaction time (RT) both showed evidence of MFBs and MFCs. These findings suggest that MFBs and MFCs can be attributed to processing that occurs prior to response selection. No dissociations between P300 latency and RT measures were found for 'present' responses across the single and multiple feature judgements. However, for 'absent' responses, partial dissociations were found between these measures, and partial errors and longer response execution intervals were observed more often when an object contained some target features. These findings suggest that response priming contributes to MFCs, but may not contribute to MFBs.

Adult↗

PubMed2001

Memory for facial expressions in social phobia.

Memory biases toward threat have been documented in several anxiety disorders, but contradictory findings have recently been reported in social phobics' recognition of facial expressions. The present study examined recognition memory in clients with social phobia, in an effort to clarify previous inconsistent results. Just before giving a speech to a live audience, social phobia clients and normal controls viewed photographs of people with reassuring and threatening facial expressions. The stimuli were later presented again alongside photographs of the same person with a different facial expression, and participants chose which face they had seen before. Individuals with social phobia were less accurate at recognizing previously seen photographs than controls, apparently due to state anxiety. In contrast, social phobics did not show a memory bias toward threatening facial expressions. Theoretical and treatment implications are discussed.

Adult↗

PubMed2000

Executive control is disturbed in schizophrenia: evidence from event-related potentials in a Go/NoGo task.

BACKGROUND: Schizophrenic patients suffer from cognitive and attentional deficits, particularly from failure of executive control functions. METHODS: This study investigated the cortical organization of executive control in schizophrenic patients and healthy control subjects using event-related potentials (ERPs). Event-related potentials were collected while subjects performed an auditory Go/NoGo task that required response inhibition. To exclude stimulus discriminability and early stimulus processing to confound results, stimuli were adjusted to the subject's individual discrimination ability and were presented in a simple and a difficult version. RESULTS: Schizophrenic patients performed similar to control subjects in the Go condition but worse than control subjects in the NoGo condition that required response inhibition. Event-related potentials revealed the neurophysiological substrate of this dysfunction. In the Go conditions, both healthy control subjects and schizophrenic patients showed the same voltage pattern. In the NoGo condition, control subjects and patients showed similar cortical activation only during early processing (N2 time window). However, in later stages of processing (P3 time window), healthy subjects showed left lateralization of ERPs over frontal areas while schizophrenic patients did not. CONCLUSIONS: We conclude that schizophrenic patients exhibit deficient processing in a neuronal network, including left frontal areas, that is involved in later stages of executive control function.

Adult↗

PubMed2003

Multi-channel evoked response detection using only phase information.

The phase consistency of contiguous segments of the electroencephalogram (EEG) has been used in the detection of evoked responses to rhythmic stimulation. One of such techniques is the component synchrony measure (CSM), which is often used since the threshold for the detection task is easily obtained based on the estimates of asymptotic sample distribution. In this work we investigated the appropriateness of such thresholds for practical number of segments (M). The performance of CSM was next evaluated by Monte Carlo simulations with different signal-to-noise ratios (SNR) and values of M, and the results, compared with those for the magnitude-squared coherence. A way of improving the detection with CSM was also proposed, by suggesting the estimation taking into account the mean phase angle of a set of N signals. This multivariate detector was evaluated in simulations and an illustration of the technique was also given with the EEG of 14 subjects during photic stimulation. In simulated signals with equal SNR, the detection rate with this multivariate measure increased with N. The application to EEG data lead to similar results in 70% of the subjects, which suggests that improvements might be expected when more signals are available to detect evoked responses in EEG.

Acoustic Stimulation↗

PubMed1998

The effects of increasing resource demand on vigilance performance in adults with schizophrenia or developmental attentional/learning disorders: a preliminary study.

The goal of this study was to assess whether degree of information processing load differentially affects vigilance performance in patients with schizophrenia as compared to normal controls or patients with other attentional disorders. We contrasted the performance of clinically stable outpatients with schizophrenia (n = 18), with that of normal controls (n = 17), and adults with developmental attentional/learning disorders (n = 13) on simple and demanding versions of a visual continuous performance test (CPT). Patients with schizophrenia were significantly impaired on both versions of the CPT compared to normal controls, and showed a significant decline in perceptual sensitivity and significantly more omission errors with increased processing demands. Compared to adults with developmental attentional/learning disorders, patients with schizophrenia manifested a tendency toward a decline in perceptual sensitivity. There were no significant differences between groups on a measure of response bias. The data support the hypothesis that patients with schizophrenia have insufficient information processing resources to cope with higher processing demands on effortful attention tasks. Further study comparing schizophrenic patients with patients who have other neuropsychiatric disorders, controlling for severity of illness, is required to determine the specificity of this deficit in schizophrenia.

Adult↗

PubMed2000

Crossmodal links between vision and touch in covert endogenous spatial attention.

The authors report a series of 6 experiments investigating crossmodal links between vision and touch in covert endogenous spatial attention. When participants were informed that visual and tactile targets were more likely on 1 side than the other, speeded discrimination responses (continuous vs. pulsed, Experiments 1 and 2; or up vs. down, Experiment 3) for targets in both modalities were significantly faster on the expected side, even though target modality was entirely unpredictable. When participants expected a target on a particular side in just one modality, corresponding shifts of covert attention also took place in the other modality, as evidenced by faster elevation judgments on that side (Experiment 4). Larger attentional effects were found when directing visual and tactile attention to the same position rather than to different positions (Experiment 5). A final study with crossed hands revealed that these visuotactile links in spatial attention apply to common positions in external space.

Adult↗

PubMed2003

Deleterious effects of alcohol intoxication: diminished cognitive control and its behavioral consequences.

The authors tested the hypothesis that impaired behavioral performance during intoxication results partly from alcohol's deleterious effects on cognitive control. The impact of alcohol on perseverative behavior was examined with an n-back working memory task that included manipulations of task complexity and prepotency of inclinations to respond or withhold responding. Thirty-two social drinkers (16 men) participated in either an alcohol (.075g/100ml) or a no-alcohol condition. Alcohol increased perseveration of prepotent, task-inappropriate response patterns only under cognitively demanding (heavy memory load) conditions. This effect was evident for both commission errors (response persistence despite contingencies altered to require restraint) and omission errors (failure to respond when contingencies were revised to encourage action). Findings suggested that alcohol-induced perseveration arises from impairments in cognitive control.

Adult↗

PubMed2003

Invisible overtures: fears of rejection and the signal amplification bias.

Four studies demonstrated that fears of rejection prompt individuals to exhibit a signal amplification bias, whereby they perceive that their overtures communicate more romantic interest to potential partners than is actually the case. The link between rejection anxieties and the bias was evident regardless of whether fears of rejection were assessed in terms of chronic attachment anxiety or were induced by reflection on a previous rejection experience. Mediation analyses suggested that the bias stems in part from an expected-augmenting process, whereby persons with strong fears of rejection incorrectly assume that the recipient of their overtures will take their inhibitions into account when interpreting their behavior. Implications for understanding the link between attachment anxiety and loneliness and for designing social skills interventions are discussed.

Adolescent↗

PubMed2006

Framing discrimination: effects of inclusion versus exclusion mind-sets on stereotypic judgments.

Three studies investigated how inclusion versus exclusion strategies differentially lead to stereotypic decisions. In inclusion strategies, suitable targets are selected from a list of candidates, whereas in exclusion strategies, unsuitable candidates are eliminated. Across 2 separate target domains (Study 1: male and female politicians; Studies 2 and 3: African American and European American basketball players), exclusion strategies, as compared with inclusion strategies, elicited higher levels of both sensitivity stereotyping (i.e., greater difficulty distinguishing among members of stereotyped groups) and criterion stereotyping (i.e., setting different decision thresholds for judging members of different groups; see M. R. Banaji & A. G. Greenwald, 1995). Thus, the strategy used during decision making can influence the final decision via 2 theoretically distinct stereotyping mechanisms.

Adolescent↗

PubMed2003

Can blindness to response-compatible stimuli be observed in the absence of a response?

Blindness to response-compatible stimuli is the finding that targets are identified less accurately when presented during the planning or execution of a congruent response (e.g., right arrow presented during a right keypress) versus an incongruent response (e.g., right arrow presented during a left keypress). Accounts of this effect suggest the planning and execution of a response are critical to its observation. Five experiments investigated whether a blindness effect would be observed in the absence of a planned response. Results suggest that a planned response is not necessary to observe a content-specific blindness effect and that the blindness effect may actually comprise both an action-related component and a symbolic component that is distinct from the action-planning system.

Adult↗

PubMed2006

Sequence learning and selection difficulty.

The authors studied the role of attention as a selection mechanism in implicit learning by examining the effect on primary sequence learning of performing a demanding target-selection task. Participants were trained on probabilistic sequences in a novel version of the serial reaction time (SRT) task, with dual- and triple-stimulus participants having to ignore irrelevant items in the SRT display. Despite large performance decrements under dual- and triple-stimulus configurations, testing under single-stimulus conditions revealed no impairment to sequence learning. These findings suggest that implicit sequence learning is resistant to disruption of the selection process. Results are discussed in terms of a componential model of attention and in relation to the implicit-explicit distinction.

Adolescent↗

PubMed2006

The attentional white bear phenomenon: the mandatory allocation of attention to expected distractor locations.

The authors devised a prestimulus-probe method to assess the allocation of attention as a function of participants' top-down expectancies concerning distractor and target locations. Participants performed the flanker task, and distractor locations remained fixed. On some trials, instead of the flanker display, either 2 simultaneous dots or a horizontal line appeared. The dot in the expected distractor location was perceived to occur before the dot in the expected empty location, and the line appeared to extend from the expected distractor location to the expected empty location, suggesting that attention is allocated to expected distractor locations prior to stimulus onset. The authors propose that a process-all mechanism guides attention to expected locations of all stimuli regardless of task demands and that this constitutes a major cause for failures of selective attention.

Adult↗

PubMed2006

The beneficial effects of additional task load, positive affect, and instruction on the attentional blink.

The attentional blink reflects the impaired ability to identify the 2nd of 2 targets presented in close succession--a phenomenon that is generally thought to reflect a fundamental cognitive limitation. However, the fundamental nature of this impairment has recently been called into question by the counterintuitive finding that task-irrelevant mental activity improves attentional blink performance (C. N. L. Olivers & S. Nieuwenhuis, 2005). The present study found a reduced attentional blink when participants concurrently performed an additional memory task, viewed pictures of positive affective content, or were instructed to focus less on the task. These findings support the hypothesis that the attentional blink is due to an overinvestment of attentional resources in stimulus processing, a suboptimal processing mode that can be counteracted by manipulations promoting divided attention.

Adolescent↗

PubMed2006

Toward a formal theory of flexible spatial behavior: geometric category biases generalize across pointing and verbal response types.

Three experiments tested whether geometric biases--biases away from perceived reference axes--reported in spatial recall tasks with pointing responses generalized to a recognition task that required a verbal response. Seven-year-olds and adults remembered the location of a dot within a rectangle and then either reproduced its location or verbally selected a matching choice dot from a set of colored options. Results demonstrated that geometric biases generalized to verbal responses; however, the spatial span of the choice set influenced performance as well. These data suggest that the same spatial memory process gives rise to both response types in this task. Simulations of a dynamic field model buttress this claim. More generally, these results challenge accounts that posit separate spatial systems for motor and verbal responses.

Adult↗

PubMed2003

Long-term semantic memory versus contextual memory in unconscious number processing.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory.

Attention↗

PubMed2003

Does familiarity change in the revelation effect?

The revelation effect describes the increased tendency to call items "old" when a recognition judgment is preceded by an incidental task. Past findings show that d' for recognition decreases following revelation, evidence that the revelation effect is due to familiarity change. However, data from receiver operating characteristic curves from 3 experiments produced no evidence of changes in recognition sensitivity. The authors illustrate how the use of a single-point measure like d' can be misleading when familiarity distribution variances are unequal. Also investigated was whether the effect depends on the revelation materials used. Neither the memorability of the revelation items, their similarity to recognition probes, nor the difficulty of the task changed the size of the effect. Thus, the revelation effect is not the result of a memory retrieval mechanism and seems to be generic and all-or-nothing. These characteristics are consistent with response bias rather than familiarity change.

Attention↗

PubMed2004

Play signaling and the perception of social rules by juvenile chimpanzees (Pan troglodytes).

Prescriptive social rules are enforced statistical regularities. The authors investigated whether juvenile chimpanzees (Pan troglodytes) recognize and use enforced statistical regularities to guide dyadic play behavior. They hypothesized (a) that proximity of adults, especially mothers of younger play partners, to play bouts will increase the play signaling of older partners and (b) that when juvenile-juvenile play bouts occur in proximity to adults, older partners will play at a lower intensity than when no adults are present. They found that older and younger partners increase their play signaling in the presence of the mothers of younger partners, particularly as the intensity of play bouts increases. In contrast to their hypothesis, older partners played more roughly when the mothers of younger partners were in proximity. These results suggest that juvenile chimpanzees increase play signaling to prevent termination of the play bouts by mothers of younger partners.

Age Factors↗

PubMed2005

A comparative study of the use of visual communicative signals in interactions between dogs (Canis familiaris) and humans and cats (Felis catus) and humans.

Dogs' (Canis familiaris) and cats' (Felis catus) interspecific communicative behavior toward humans was investigated. In Experiment 1, the ability of dogs and cats to use human pointing gestures in an object-choice task was compared using 4 types of pointing cues differing in distance between the signaled object and the end of the fingertip and in visibility duration of the given signal. Using these gestures, both dogs and cats were able to find the hidden food; there was no significant difference in their performance. In Experiment 2, the hidden food was made inaccessible to the subjects to determine whether they could indicate the place of the hidden food to a naive owner. Cats lacked some components of attention-getting behavior compared with dogs. The results suggest that individual familiarization with pointing gestures ensures high-level performance in the presence of such gestures; however, species-specific differences could cause differences in signaling toward the human.

Animal Communication↗