Cognitive precedence for local information in hierarchical stimulus processing by pigeons.

Four experiments investigated the processing of hierarchical stimuli by pigeons. Using a 4 alternative divided–attention task, 4 pigeons were food-reinforced for accurately identifying letters arranged as either hierarchical global- or local-relevant stimuli or as size-matched filled stimuli. Experiment 1 found that task acquisition was faster with local-relevant than global-relevant stimuli. This difference was not due to letter size. Experiment 2 demonstrated successful transfer to a novel irrelevant letter configuration. Experiments 3 and 4 tested pigeons' responses to conflict probe stimuli composed of equally discriminable relevant letters at each level. These tests revealed that all of the pigeons showed a cognitive precedence for local information early in processing, with the pigeons using different cues to initiate the processing of global information. This local advantage contrasts with previously reported results for humans and pigeons but is similar to that reported for nonhuman primates. Alternatives attempting to reconcile these contrasting comparative results are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shifting attention between global features and small details: an event-related potential study

In two experiments, large letters H or Z composed of small letters (also H or Z) were presented. Subjects had to make a two-choice motor response (e.g. H--left key, Z--right key). A cue presented 500 ms before the letter indicated which level (global or local) was relevant. In Experiment I, a third letter (T) sometimes appeared either at the cued or the non-cued level; in the former case, subjects had to shift their attention and to respond to stimulus features located at the non-cued level. The interference effect (RT delay in response to incongruent stimuli as compared to congruent ones) was larger when the local, rather than global, level was cued. A slow anterior negativity preceding globally-cued stimuli and shorter N1 and P2 ERP component latencies to these stimuli indicated better preparation for processing of global, as compared to local, stimulus features. The shift from local to global focus yielded a larger increase of RT, error rate, and of the P600 latency than the global-to-local shift. The P600 latency changes were parallel to those of RT. In Experiment II, the attentional shift was provoked by stimulus color red-colored letters meant that the cue was invalid, and thus, subjects had to respond to the non-cued level. Neither the interference nor the attentional shift demonstrated any asymmetry between the global and local levels. ERPs also did not differ substantially after local and global cues. In the condition demanding a shift of focus (invalid cue, incongruent letter), a positive deflection of the lateralized readiness potential indicated the activation of the wrong response channel. The large RT increment in this condition was not accompanied by an increase of the P600 latency. Two possible mechanisms of attentional shift may be proposed, the first related to perceptual processes (e.g. an additional visual search), and the second, to the competition between two response intentions.     

Component mechanisms underlying the processing of hierarchically organized patterns: Inferences from patients with unilateral cortical lesions.

Subjects identified target letters that occurred randomly at the local or global level in a divided attention task. The visual angle of the stimuli was varied. Neurologically intact controls showed a reaction time advantage for local targets which increased as visual angle increased. Patients with lesions centered in the posterior superior temporal gyrus (STG) showed a larger local advantage than controls if the lesion was on the right and a global advantage if the lesion was on the left. STG patients were no more influenced by visual angle than were controls. Control subjects also showed the usual interference of global distractors on responding to local targets. STG patients showed little evidence of interference. Control patients with lesions centered in the rostral inferior parietal lobe performed normally. The findings suggest that several component mechanisms are involved in the processing of hierarchical levels of structure, each linked to specific anatomical regions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global precedence: The effect of exposure duration.

Stimuli consisting of large letters constructed from small letters were presented to 26 undergraduates for 10, 40, or 100 msec, and Ss were required to identify either the large letters or the small letters. At the 10-msec exposure duration, only unidirectional or global to local interference was observed. This finding is consistent with D. Navon's (see record 1978-11488-001) global precedence hypothesis. However, at the longer exposure durations equivalent global to local and local to global interference patterns were observed. Results limit the generality of any global precedence hypothesis, either perceptual or attentional, to conditions in which there are large discrepancies in the quality of the local and global information. (French abstract) (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming of attention to local or global levels of visual analysis.

Humans can shift attention between parts and wholes, as shown in experiments with complex hierarchical stimuli, such as larger, global letters constructed from smaller, local letters. In these experiments, a target stimulus appears at either the local or the global level, with a distractor at the other level. A shift of attention between levels is said to be demonstrated through a form of priming, whereby targets at one level are presented with a higher probability than at the other level. This base-rate type of priming can facilitate speed of responding to targets, as seen in shorter reaction times to targets at the primed level. Experiment 1 demonstrated such a priming effect in pigeons. Experiment 2 confirmed this priming, by showing that accuracy remained high for familiar targets, at either level, even when distractors at the other level were novel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A spatial frequency account of the detriment that local processing of Navon letters has on face recognition.

Five minutes of processing the local features of a Navon letter causes a detriment in subsequent face-recognition performance (Macrae & Lewis, 2002). We hypothesize a perceptual after effect explanation of this effect in which face recognition is less accurate after adapting to high-spatial frequencies at high contrasts. Five experiments were conducted in which face-recognition performance was compared after processing high-contrast Navon stimuli. The standard recognition deficit was observed for processing the local features of Navon stimuli, but not if the stimuli were blurred (Experiment 1) or if they were of lower contrast (Experiment 2). A face-recognition deficit was observed after processing small, high-contrast letters equivalent to local processing of Navon letters (Experiment 3). Experiments 4 and 5 demonstrated that recognition of bandpass-filtered faces interacted with the type of Navon processing, in which the recognition of low-pass filtered faces was better following local rather than global processing. These results suggest that the Navon effect on subsequent face recognition is a perceptual phenomenon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organizational and spatial dynamics of attentional focusing in hierarchically structured objects.

Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task, participants successively identified the global and local letters in the same trial. Overall response latencies were generally longer for larger versus smaller global objects and for three-level versus two-level object structure, indicating that attentional focusing time increases both with the magnitude of change in attentional aperture size and with the number of traversed levels of object structure. Additional experiments showed that this pattern is unique to tasks that require dynamic attentional focusing. Taken together, the results support a hierarchical object-based-spatial model of attentional focusing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Hypnotic susceptibility and performance on various attention-specific cognitive tasks.

In 2 experiments, 52 undergraduates were administered the Harvard Group Scale of Hypnotic Susceptibility, Form A, and were divided into groups with high and low hypnotic susceptibility (HS). In Exp I (32 Ss), time-to-location of a target in a visual search was assessed. For this task, the letter Z was embedded within either straight- or round-form letters. Results indicate that Ss of high HS were significantly faster than those of low HS in locating the embedded letter. Exp II (20 Ss) investigated performance on single- and double-digit arithmetic problems as a function of HS level. Ss were presented with addition problems and asked to complete them within 60 sec. Ss of high HS completed a significantly greater number of double- but not single-digit problems within this time than did Ss of low HS. Results are discussed in terms of the 2 groups' differing strategies or operations in the performance of cognitive tasks. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The roles of stimulus-response compatibility and mental rotation in mirror-image and left-right decisions.

Examined the relative roles of mental rotation and stimulus-response (SR) compatibility in mirror-image and left-right decisions. 15 Ss, aged 19–43 yrs, were shown rotated letters and asked to indicate whether the letters were normal or backward (mirror-image task). Ss were then asked whether a dot would be located to the left or right of each letter if the letter was upright (viewer-centered left-right task) or if the letter was both upright and normal (letter-centered left-right task). The functions relating reaction time (RT) to angular orientation were parallel across the 3 tasks, suggesting that SR compatibility played no role, and that the Ss mentally rotated the letters to the upright in each case. A marked increase in RT to backward letters in the letter-centered task suggested a 2nd rotation in depth to restore the letters to normal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sequential priming in hierarchically organized figures: Effects of target level and target resolution.

Three experiments are reported in which participants identified target letters that appeared at either the global or local level of hierarchically organized stimuli. It has been previously reported that response time is facilitated when targets on successive trials appear at the same level (L. M. Ward, 1982; L. C. Robertson, 1996). Experiments 1 and 2 showed that this sequential priming effect can be mediated by target-level information alone, independent of the resolution, or actual physical size, of targets. Target level and resolution were unconfounded by manipulating total stimulus size, such that global elements of the smaller stimuli subtended the same amount of visual angle as local elements of the larger stimuli. Experiment 3, however, showed that when level information is less useful than resolution in parsing targets from distractors, resolution does become critical in intertrial priming. These data are discussed as they relate to the role of attention in local vs. global (part vs. whole) processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of injected dose for brain mapping on the ECAT HR+: activation maps for a parametric verbal working memory task

The success of the 15O-water PET technique to localize statistically significant changes in regional cerebral blood flow is dependent on factors such as the activity level injected and the magnitude of the flow change. Undetectable changes may occur if insufficient activity is injected leading to high levels of statistical noise or the task performed results in only small changes in blood flow. To explore the relationship between injected activity and statistical significance, we performed a series of studies with the ECAT EXACT HR+, a high resolution PET tomograph. A parametric verbal working memory task (the N-back task) was selected to examine the relationship between regional cerebral blood flow and working memory load across a range of injected doses of 15O-water. At each activity level the volunteers were required to perform four different levels of the N-back task, a task in which a letter displayed on a monitor is matched with the letter displayed N letters previously. With increasing N, this task places increased load on working memory. For this study, 5, 10, and 15 mCi of 15O-water were injected into nine normal volunteers. The complete sequence of four tasks (N = 0, 1, 2, and 3) at three activity levels was repeated twice, for a total of 24 injections of 15O-water. We show that the peak count rate performance for the HR+ is approached at injected activity levels of 15O-water around 15 mCi. For this particular choice of N-back task, robust activation maps can nevertheless be obtained with as little as 5 mCi injected dose.     

First came the trees, then the forest: Developmental changes during childhood in the processing of visual local-global patterns according to the meaningfulness of the stimuli.

This study investigated how global and local perceptual processes evolve during childhood according to the meaningfulness of the stimuli. Children had to decide whether visually presented pairs of items were identical or not. Items consisted of global forms made up of local forms. Both global and local forms could represent either objects or nonobjects. In dissimilar pairs, items differed at one level (target level), while the other level included similar forms on both sides (irrelevant level). The results indicate an evolution from local preference at 4 years of age to adult-like global preference at 9 years of age. Moreover, as previously reported in adults, regardless of age, identification impaired performance when the irrelevant level was made of objects and the target level was made of nonobjects (interference). However, in younger children, this interference existed even when objects were present at all levels, suggesting that the strategy used to perform the comparison task also varied according to age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparing for novel versus familiar events: Shifts in global and local processing.

Six experiments examined whether novelty versus familiarity influences global versus local processing styles. Novelty and familiarity were manipulated by either framing a task as new versus familiar or by asking participants to reflect upon novel versus familiar events prior to the task (i.e., procedural priming). In Experiments 1–3, global perception was enhanced after novelty priming or framing, whereas familiarity priming facilitated local perception relative to a control group. In Experiment 4, participants used more inclusive categories under novelty priming and narrower categories under familiarity priming. In Experiments 5–6, participants construed actions and products more abstractly when these were framed as novel as compared to familiar. These results support the construal level theory (N. Liberman & Y. Trope, 2008; Y. Trope & N. Liberman, 2003) contention that having less direct experience is associated with using higher construal levels. Implications of the findings for research on mood, processing styles, stereotypes, and consumer research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention allocation modulates the processing of hierarchical visual patterns: A comparative analysis of capuchin monkeys (Cebus apella) and humans.

Humans show a global advantage when processing hierarchical visual patterns, and they detect the global level of stimulus structure more accurately and faster than the local level in several stimulus contexts. By contrast, capuchins (Cebus apella) and other monkey species show a strong local advantage. A key factor which, if manipulated, could cause an inversion of this effect in monkeys is still to be found. In this study, we examined whether it was possible to induce attention allocation to global and local levels of perceptual analysis in capuchin monkeys and if by doing so, their local dominance could be reversed. We manipulated attentional bias using a matching-to-sample (MTS) task where the proportion of trials requiring global and local processing varied between conditions. The monkeys were compared with humans tested with the same paradigm. Monkeys showed a local advantage in the local bias condition but a global advantage in the global bias condition. The role of attention in processing was confined to the local trials in a first phase of testing but extended to both local and global trials in the course of task practice. Humans exhibited an overall global dominance and an effect of attentional bias on the speed of processing of the global and local level of the stimuli. These results indicate a role for attention in the processing of hierarchical stimuli in monkeys and are discussed in relation to the extent to which they can explain the differences between capuchin monkeys and humans observed in this and other studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Fathers of persons with mental illness: a preliminary study of coping capacity and service needs

The effects of a single dose of caffeine on specific information processing operations were examined by using a visual selective attention task in which subjects were asked to select between a left and right hand response on the basis of two different target letters. The target was presented on a predefined position in the visual field and was either presented alone or with flanker letters, calling for the correct, the incorrect or no specific response. A dose of 3 mg/kg body weight caffeine or lactose, dissolved in a cup of decaffeinated coffee, was administered double blind and deceptively to overnight abstinence coffee drinkers. Behavioural measures were supplemented by psychophysiological measures. The present results replicated the basic findings obtained in this paradigm. The results indicated that the time to localise the target decreased and response preparation started earlier after caffeine than after placebo. These caffeine effects did not interact with the time subjects spent on the task or with the reaction time distribution, which might be due to a high level of practice.     

Spatial attention and cuing to global and local levels of hierarchical structure.

Five experiments investigated the role of attention in identifying global and local targets in hierarchically structured patterns. Hierarchical patterns were presented at a variable stimulus onset asynchrony (SOA) either after a cue (4 arrows or shaded boxes) or after no cue. Targets occurred at the cued level 80% of the time and at the uncued level 20%. On uncued trials, target level probability was .5. Global cues produced benefits for both global and local targets over SOA on cued trials. Local cues produced benefits only for local targets. For uncued trials, responses favored local targets overall when interspersed with locally cued trials but favored global targets when interspersed with globally cued trials. The role of an attentional window and discrete distribution of attention over global and local levels of hierarchical patterns are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Presentation rate and order of approximation to English as determinants of short-term memory.

Presented sequentially, to 30 undergraduates, 28 sequences of 10 letters representing 0- and 2nd-order approximations to English at presentation rates of 3 letters/sec, 2 letters/sec, and 1 letter/sec. Groups of 10 Ss received each rate of presentation. In agreement with previous studies, the increased time for input processing available at the slower presentation rates produced greater differentiation in the immediate recall of 0- and 2nd-order approximations. Additional analyses suggest that the increased differentiation was attributable to both a greater increase in the efficiency of processing order information and more rapid processing of individual letters in the 2nd-order approximations. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separability and integrality of global and local levels of hierarchical patterns.

Used a constrained classification task to examine the perceptual relations between global and local levels in hierarchical patterns composed of many, relatively small elements and those composed of few, relatively large elements. In 4 experiments, 52 18–35 yr olds made classifications based on form or texture or according to the shape of the configuration or the elements. Results indicate that configural and elemental levels were perceptually separable for many-element patterns when processed as form and texture. Ss could attend to either level without being affected by variation along the irrelevant dimension. However, when the same many-element patterns were processed for global and local shape. Ss could not selectively attend to either level. For few-element patterns, global configuration and local elements appeared to be perceptually integral dimensions. Results are discussed in terms of the global precedence hypothesis and explanations of integral and separable dimensions. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming and response selection processes in letter classification and identification tasks.

The processing of isolated visual letters was studied by means of a priming paradigm. In alphabetic (letter vs nonletter) classification, any letter prime reduced response times to letter targets. Additional facilitation occurred only with primes physically identical to the target. In letter naming, facilitation was seen with primes nominally identical to the target even when they were physically different. This result is not due to phonological priming because phonologically similar primes had no effect on naming times. Primes nominally different from the target but physically similar to it increased naming times. The classification task seems to be performed through the global monitoring of stored visual knowledge of letters. In contrast, the absolute identification of letters appears to rest on a signal-to-noise statistic derived from an abstract encoding of letter identities. Connectionist simulations provide support for these proposals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parallel and competitive processes in hierarchical analysis: Perceptual grouping and encoding of closure.

The role of perceptual grouping and the encoding of closure of local elements in the processing of hierarchical patterns was studied. Experiments 1 and 2 showed a global advantage over the local level for 2 tasks involving the discrimination of orientation and closure, but there was a local advantage for the closure discrimination task relative to the orientation discrimination task. Experiment 3 showed a local precedence effect for the closure discrimination task when local element grouping was weakened by embedding the stimuli from Experiment 1 in a background made up of cross patterns. Experiments 4A and 4B found that dissimilarity of closure between the local elements of hierarchical stimuli and the background figures could facilitate the grouping of closed local elements and enhanced the perception of global structure. Experiment 5 showed that the advantage for detecting the closure of local elements in hierarchical analysis also held under divided- and selective-attention conditions. Results are consistent with the idea that grouping between local elements takes place in parallel and competes with the computation of closure of local elements in determining the selection between global and local levels of hierarchical patterns for response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)