Multiple-feature discrimination faster than single feature discrimination within the same object?

In the present study, we investigated whether judging the presence of multiple features within an object would be superior to judging the presence of only one feature. Feature discriminability and the number of features to discriminate within an object were varied. Specific features were judged as present or absent. Results showed that judging the presence of two or three features was faster than judging the presence of the less discriminable of these two or three features alone (multiple-feature benefits). These findings suggest that relevant features within an object activate (prime) a decision or response in a parallel, asynchronous fashion based on discriminability (Miller, 1982a). The ability of a response priming model, a response mapping model, and a template model to account for multiple feature benefits is discussed.     

Interference From Multi-dimensional Objects During Feature and Conjunction Discriminations

Feature discrimination performance within an attended object and interference from irrelevant, multi-dimensional objects (distractors) were examined in a two-choice, response compatibility paradigm. Results showed that the amount of interference by multi-dimensional distractors was dependent on three factors: (1) the discriminability of the incompatible, task-relevant distractor features; (2) the number of incompatible, task-relevant distractor features; and (3) whether the task-relevant, incompatible features matched the task goals. The most interesting finding was that additive priming effects were found for multiple, task-relevant features that matched the task goals, whether these features were present in the attended object or in the ignored object. Models that assume that each task-relevant feature primes its corresponding decision/response asynchronously and that this priming is combined to meet a decision/response criterion (at least when attended) can account for distractor interference during conjunction discriminations. Implications of these findings for feature integration models, template models, and a response selection model are discussed.     

Reaction time and movement time as measures of stimulus evaluation and response processes

Reaction time has been divided into the time to initiate a response (RT) and the time to execute the motor response (MT) in many chronometric studies of intelligence. Our purpose was to determine which cognitive processes are reflected by RT and MT. To accomplish this, the latency of the P300 wave of the event-related potential was recorded concurrently with RT and MT measures in three experiments. P300 latency reflects the duration of stimulus evaluation relatively independently of response processes. In the first experiment, a Sternberg memory task was employed to manipulate stimulus classification requirements. In the second, the subjects' emphasis on either speed or accuracy of responding was examined during a task that also manipulated stimulus evaluation time. In the third experiment, a Stroop-like task was used to examine response processes. RT and P300 latency varied with manipulations of stimulus evaluation time, whereas MT varied with difficulty of motor execution. MT was also affected by stimulus classification processes. Both RT and MT were sensitive to processes involved in response bias and preparation. The possibility that the correlations of RT and MT with measures of intelligence are due to effects on a common stage of information processing cannot be rejected in the light of these results.     

Conjunction benefits and costs reveal decision priming for first-order and second-order features

Across two experiments, decision priming was examined for conjunctions composed of first-order or first- and second-order stimulus features. Observers indicated the presence or absence of one or two features in a Gabor stimulus. When a pair of stimulus features differed in their speed of discrimination, responses indicating the presence of a conjunction were faster than those for the single feature for which discrimination was slowest (conjunction benefits). Also, responses indicating the absence of a conjunction were delayed if one of the features was present (conjunction costs). These results show that first- and second-order features can prime decisions about the presence of a conjunction and suggest that the two kinds of signals can be combined at a decision stage after the discrimination of stimulus properties has begun for each system.     

Mental ability and the effect of pattern violation discrimination on P300 and mismatch negativity

The relation between mental ability and the ability to detect auditory pattern violations was examined using event-related potential measures, specifically P300 and mismatch negativity (MMN). Thirty female volunteers were presented with a two tone alternating pattern containing infrequent repetition violations in passive (ignore) then active response conditions. Task difficulty was manipulated by varying the tonal separation between the two constituent tones of the pattern, i.e., separated by 1 or 6 semitones. In the active pattern violation discrimination condition, the greater difficulty of the 1 semitone discrimination was confirmed by reduced accuracy, more false positive responses, longer response times, and greater variability in response times than for 6 semitones. Higher ability (HA) was associated with greater response accuracy, shorter response times, less variable response times, shorter P300 latency, and greater P300 amplitude, predominantly in the more difficult 1 semitone condition. These effects are indicative of greater facility and speed of discriminating pattern violations for HA. In the passive condition, HA was associated with larger MMN amplitude to the deviant tones in both semitone conditions. The MMN effect indicates that the facility in pattern violation discrimination develops prior to consciousness, and cannot be attributed to conscious processes like focussed attention.     

The temporal selectivity of additive factor effects on the reaction process revealed in ERP component latencies

An experiment was conducted to relate individual components of the event-related brain potential to specific stages of information processing in a two-choice reaction time (RT) task in a group of undergraduate students. Specifically, the latency of the P300 component and the lateralized readiness potential (LRP) were studied as a function of variations in stimulus degradation and response complexity. It was hypothesized that degrading the stimulus would delay the P300 and LRP to the same extent as RT, and that increasing response complexity would affect RT but not P300 latency. The extant literature did not permit any hypothesis regarding the effect of response complexity on LRP latency. The two task variables were found to have additive effects on RT. As predicted, variations in stimulus degradation influenced the latencies of both components, whereas alterations in response complexity had no effect on P300 latency. A significant new finding was that the onset latency of the LRP remained unchanged across levels of response complexity. The overall pattern of results supports the notion of temporal selectivity of stage manipulations that is derived from discrete stage models of human information processing. Furthermore, these results refine the functional interpretation of the LRP by indicating that within the conceptual framework of a stage model the processes this component indexes succeed the start of response choice but precede the start of motor programming.     

The chronometry of mental ability: An event-related potential analysis of an auditory oddball discrimination task

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA) displayed more accurate discriminations, faster response time, larger P300 amplitude, and shorter P300 and mismatch negativity (MMN) latency than lower ability participants (LA). Task difficulty effects demonstrated with variation in mask type indicate that the mask does not interfere with the detection of the deviant target stimulus, but rather that the target and mask are integrated as a single compound stimulus. The temporal effects suggest that the speed of accessing short-term memory is faster for HA than LA and, on the basis of the MMN latency, the effect is accomplished automatically, without focused attention. Moreover, the pattern of results obtained with these data support the view that the accuracy effects are determined by processing speed rather than discrimination ability. Comparator models that accommodate these effects are discussed.     

Repetition priming reveals sustained facilitation and transient inhibition in reaction time

Reaction time (RT) in a detection or a location discrimination task increases when a target is repeatedly presented at the same location (inhibition), whereas RT decreases in feature (color or orientation) discrimination tasks (facilitation; Y. Tanaka & S. Shimojo, 1996a). Here, the time course of inhibition and facilitation was examined, using a repetition priming paradigm. Results indicate that inhibition occurred only in the immediately successive trial, whereas facilitation accumulated over several trials with location repetition. Moreover, inhibition and facilitation occurred in a task-relevant manner: Detection-location discrimination tasks produced transient RT increase, whereas feature discrimination tasks produced cumulative RT decrease. These results suggest a functional dissociation between spatial orienting and feature analysis, as well as top-down modulations by tasks leading to different types of visual memory.     

Relationship between priming and recognition in deterministic and probabilistic sequence learning

Exposure to a repeating sequence of target stimuli in a speeded localization task can support both priming of sequence-consistent responses and recognition of sequence components. In 3 experiments with both deterministic and probabilistic sequences, the authors used a novel procedure in which measures or priming and recognition were taken concurrently and asked whether these measures can be dissociated. In all of these experiments, both measures were above chance at the group level and no evidence of dissociation was found. Item-level analyses of the data in Experiment 3 did reveal dissociations in that (a) recognition judgments were affected by response speed independently of old-new status and (b) items that were not discriminated in recognition nonetheless showed priming. However, the authors show that these data, together with the group-level results, are compatible with a formal model in which priming and recognition are based on a single common memory variable.     

Mental ability,P300, and mismatch negativity: Analysis of frequency and duration discrimination

Individual differences in mental ability (MA) were examined with event-related potentials (ERP). In addition to using an auditory frequency discrimination task, a duration discrimination task was used to elicit P300 and mismatch negativity (MMN) components of the ERP. Frequency and duration P300 latencies explained 9% and 10% of variance of MAB performance scores independently of each other and commonly 28% of variance. The finding that duration P300 latency explained variance of MA independent of that explained by frequency P300 latency, suggests that temporal information processing is partly dissociable from processing of frequency information in its prediction of MA. Duration and frequency MMNs were shown to be indices of discrimination ability and predicted 11% of variance of MAB performance scores. The outcome of the present study not only emphasizes the importance of both mental speed and discrimination ability for MA but also points to the significance of duration- and frequency-related ERP measures for the understanding of underlying brain mechanisms.     

Amodal completion of unconsciously presented objects

In the visual environment, objects often appear behind occluding surfaces, yet they are automatically and effortlessly perceived as complete. Here, we examined whether visually occluded objects that are presented below the threshold of awareness are amodally completed. We used a priming paradigm in which participants responded to consciously perceived targets that were preceded by unconsciously presented primes. In two experiments, we show that discrimination responses to targets were faster when they were preceded by congruent shapes, regardless of whether these shapes were intact and complete or occluded by a horizontal bar. This priming effect was not produced by a partial match in features, since the occluded primes did not facilitate responses to targets that shared local features (Experiment 1) or contained only the object features that remained visible after occlusion (Experiment 2). These results show that objects presented below the threshold of awareness can be amodally completed and provide compelling evidence that unconscious processing occurs to a greater extent than previously considered.     

Episodic retrieval and feature facilitation in intertrial priming of visual search

Huang, Holcombe, and Pashler (Memory & Cognition, 32, 12-20, 2004) found that priming from repetition of different features of a target in a visual search task resulted in significant response time (RT) reductions when both target brightness and size were repeated. But when only one feature was repeated and the other changed, RTs were longer than when neither feature was repeated. From this, they argued that priming in visual search reflected episodic retrieval of memory traces, rather than facilitation of repeated features. We tested different variations of the search task introduced by Huang et al., with the aim of uncovering when priming is episodic and when feature based. We found that varying the signal strength of target against distractors had a strong effect on the priming pattern. In difficult search with low signal-to-noise ratios of target against distractors, the priming patterns were episodic. When feature contrasts between target and distractors were increased, priming of different features was independent and additive. Our results suggest that, during inefficient search,priming can be episodic but that, for more efficient search, priming from different features occurs independently. The results support two-stage (or multistage) accounts of priming in visual search.     

Intelligence and information processing during an auditory discrimination task with backward masking: an event-related potential analysis

The relation between mental ability and auditory discrimination ability was examined by recording event-related potentials from 60 women during an auditory oddball task with backward masking. Across conditions that varied in intensity and in the interval between the target and masking stimuli, the higher ability (HA) group exhibited greater response accuracy, shorter response times, larger P3 amplitude, and shorter P3 latency to target stimuli than the lower ability (LA) group. When instructed to ignore the stimuli, the HA group exhibited shorter mismatch negativity latency to deviant tones than the LA group. The greater speed and accuracy of auditory discrimination for the HA group, observed here with multiple measures, is not a consequence of response strategy, test-taking ability, or attention deployment.     

Event-related potentials elicited by automatic targets: a dual-task analysis

The role of limited capacity processes in the detection of automatic targets was investigated in a dual-task paradigm using both behavioral and event-related brain potential (ERP) measures. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic (POC) showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). In addition, the latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of two separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses.     

Visual objects can potentiate a grasping neural simulation which interferes with manual response execution

Previous studies on visuomotor priming have provided insufficient information to determine whether the reach-to-grasp potentiation of a non-target object produces a specific effect during response execution. In order to answer this question, subjects were instructed to reach and grasp a response device with either a power or a precision grip, depending on whether the stimulus they saw was empty or full. Stimuli consisted of containers (graspable with either a power or a precision grip), with non-graspable stimuli added as a control condition (geometrical shapes). The image of the non-target object was removed during the execution phase. Results demonstrate slower execution responses related to motor incompatibility, though conversely, no faster responses with motor compatibility. Moreover, any visuomotor priming effect required that the container be displayed during response execution. These data suggest that during response execution, motor incompatibility produces a disruptive effect likely due to competition between two cerebral events: motor control of the actual response execution and visual object reach-to-grasp neural simulation.     

Persistent repetition priming in picture naming and its dissociation from recognition memory

The current experiments investigated the longevity of repetition priming and dissociations between different memory measures. Picture-naming latencies revealed robust repetition priming in four separate studies: Previously named pictures were named faster than new pictures. The magnitude of this naming facilitation was stable across 1 to 6 weeks. The apparent temporal invulnerability of repetition priming was in marked contrast to the decline in episodic recognition memory across 6 weeks, suggesting a dissociation between implicit and explicit memory. Additional evidence of this dissociation was observed within each session: Naming facilitation for repeated pictures occurred regardless of whether those particular pictures were consciously recognized.     

Getting a grip on numbers: numerical magnitude priming in object grasping

To investigate the functional connection between numerical cognition and action planning, the authors required participants to perform different grasping responses depending on the parity status of Arabic digits. The results show that precision grip actions were initiated faster in response to small numbers, whereas power grips were initiated faster in response to large numbers. Moreover, analyses of the grasping kinematics reveal an enlarged maximum grip aperture in the presence of large numbers. Reaction time effects remained present when controlling for the number of fingers used while grasping but disappeared when participants pointed to the object. The data indicate a priming of size-related motor features by numerals and support the idea that representations of numbers and actions share common cognitive codes within a generalized magnitude system.     

Discrimination and reproduction of patterns: Feature measures and constraint redundancy as predictors

The statistical structure ofsamples ofpatterns [histoforms and polygons) was varied by manipulating constraint redundancy (R_c) at three levels. Both R_c and seven measures of pattern features were evaluated as predictors of reproduction errors and discrimination latency using multiple linearregression techniques. While it was possible to account for a significant proportion of performance variance from knowledge of R_c levels, feature measures accounted for more performance variance under all conditions of testing. The results were interpreted as support for the notion that patterns are processed in terms offeatures.     

Demands on attention and the role of response priming in visual discrimination of feature conjunctions

This study examined how response mapping of features within single- and multiple-feature targets affects decision-based processing and attentional capacity demands. Observers judged the presence or absence of 1 or 2 target features within an object either presented alone or with distractors. Judging the presence of 2 features relative to the less discriminable of these features alone was faster (conjunction benefits) when the task-relevant features differed in discriminability and were consistently mapped to responses. Conjunction benefits were attributed to asynchronous decision priming across attended, task-relevant dimensions. A failure to find conjunction benefits for disjunctive conjunctions was attributed to increased memory demands and variable feature-response mapping for 2- versus single-feature targets. Further, attentional demands were similar between single- and 2-feature targets when response mapping, memory demands, and discriminability of the task-relevant features were equated between targets. Implications of the findings for recent attention models are discussed.     

Cross-modality priming for people's adjectivized names: failure to support the adjectivization hypothesis

This experiment tested a prediction derived from Hollis and Valentine's 2001 adjectivization hypothesis, that having an adjectival form is the key factor that makes certain classes of proper names, i.e., country names, exhibit a common name-like pattern of long-term priming. The hypothesis predicted that, when adjectivized historical celebrity names, e.g., William Shakespeare/Shakespearean, were compared with nonadjectivized historical celebrity names, e.g., Emile Zola, cross-modality long-term priming in a familiarity decision task would occur only for nonadjectivized name stimuli. 32 students of literature, history, or philosophy (21 women and 11 men; age range 18-41 years, M age = 22.4 yr.) were tested. Priming was measured by latency of response. Analysis showed that the mean RT to primed items was faster than the mean RT to unprimed items when the prime task was presented in both visual and auditory modalities both for the adjectivized and nonadjectivized names. Contrary to the hypothesis, cross-modality priming was observed regardless of the adjectivization of name stimuli. The findings of the present experiment did not support the adjectivization hypothesis.