Perceptual grouping in schizophrenia: Replication of Place and Gilmore.

E. Place and G. Gilmore (see record 1980-25819-001) found that schizophrenics, unlike control Ss failed to utilize gestalt grouping principles in a task involving line counting. The present investigation was a replication of that study but with several methodological refinements, including the subtyping of schizophrenics, a fixed exposure duration of 15 msec, and analyses of both raw and arcsin transformed data. Ss were 10 paranoid schizophrenic, 10 nonparanoid schizophrenic, and 10 nonschizophrenic patients (mean age 31 yrs) and 10 normal undergraduates. The basic findings of Place and Gilmore held, and the refinements utilized made no difference. Results are discussed in terms of a 2-stage model of perceptual processing that describes normal perception in terms of an intitial global structuring of the stimulus field and a secondary local analysis. Schizophrenics appear to use the 2nd processing stage regardless of the stimulus condition. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual closure in schizophrenia.

The concept of closure has been more frequently investigated using normal Ss than psychotic patients. The present study utilizes schizophrenics and compares their performance with a comparable group of hospitalized nonpsychotic Ss. Taylor's (1960) test of closure was used. Tendency to closure tended to be lower for the schizophrenics than for the nonschizophrenics, with schizophrenics on drugs (and, hence, manifesting a greater degree of personality disorganization than the other schizophrenic Ss) showing no tendency towards closure. The results are related to 2 theories of schizophrenia, one which involves a deficit in the energizing or arousal systems in the brain, and the other, an inability to maintain a set in the way normal Ss do. From Psyc Abstracts 36:04:4JQ31S. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping and spatial distortion: A developmental study.

20 Ss in each of 5 age groups (kindergartners; 2nd, 4th, and 6th graders; and graduate students) estimated distances between elements in patterns illustrating the Gestalt grouping principles of proximity, similarity, closure, and good continuation. Ss of all age groups consistently judged distances between elements in the same perceptual group as smaller than physically identical distances between elements in different perceptual groups, which indicated that all Ss were sensitive to the structure of the Gestalt patterns. The magnitude of these distance distortions decreased significantly with age, which suggests that perceptual development includes improvements in the ability to disregard Gestalt groupings when the task requires selective attention to certain elements. Results are consistent with evidence that perceptual development moves from visual processing based primarily on global attributes of patterns to processing that can selectively analyze the component structure of patterns. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping by infants and preschool children.

We tested infants 6 to 8 months and children 5? years of age for their discrimination of silent intervals between elements of auditory patterns. Standard patterns consisted of six 200-ms tones, three at 440 Hz and three at 659 Hz, with 200-ms intertone intervals (XXXOOO). Contrasting patterns differed only in the addition of a silent increment following the third tone (i.e., between tone groups, XXXOOO) or following the fourth tone (i.e., within a tone group, XXXOOO). Contrasting stimuli presented to infants had increments of 200, 125, 100, or 75 ms; those presented to children had increments of 100, 75, and 50 ms. Infants detected all increments in all locations except the 75-ms increment in the between-group location, but there were no differences in performance for different increment locations. Children detected all increments, but performed significantly worse for between-group increments than for within-group increments. Thus, the context of a temporal increment influences its detectability for children, as it does for adults, indicating that children group the elements of auditory stimuli on the basis of frequency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual encoding efficiency in visual search.

The authors present 10 experiments that challenge some central assumptions of the dominant theories of visual search. Their results reveal that the complexity (or redundancy) of nontarget items is a crucial but overlooked determinant of search efficiency. The authors offer a new theoretical outline that emphasizes the importance of nontarget encoding efficiency, and they test this proposal using dot pattern stimuli adapted from W. R. Garner and D. E. Clement (1963). The results provide converging support for the importance of nontarget encoding efficiency in accounting for visual search performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping affects pitch judgments across time and frequency.

Pitch, the perceptual correlate of fundamental frequency (F0), plays an important role in speech, music, and animal vocalizations. Changes in F0 over time help define musical melodies and speech prosody, while comparisons of simultaneous F0 are important for musical harmony, and for segregating competing sound sources. This study compared listeners' ability to detect differences in F0 between pairs of sequential or simultaneous tones that were filtered into separate, nonoverlapping spectral regions. The timbre differences induced by filtering led to poor F0 discrimination in the sequential, but not the simultaneous, conditions. Temporal overlap of the two tones was not sufficient to produce good performance; instead performance appeared to depend on the two tones being integrated into the same perceptual object. The results confirm the difficulty of comparing the pitches of sequential sounds with different timbres and suggest that, for simultaneous sounds, pitch differences may be detected through a decrease in perceptual fusion rather than an explicit coding and comparison of the underlying F0s. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye movements in reading: Perceptual and cognitive processes.

This article discusses the variability of eye movement behavior. The variability exists between readers, so that the average fixation duration for sonic readers my be around 200 ms and for other readers it may be closer to 300 ms; the average saccade length for some readers may be 6 letter spaces, while for others it may be closer lo 10 letter spaces; and some readers rarely regress while others regress quite frequently. These eye movement characteristics can also be influenced by text difficulty; more difficult text leads to longer fixation durations, shorter saccades, and more regressions. More important than the between reader variability is the within reader variability that exists with each of these measures. The article also discusses research on eye movement during reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual rigidity and closure as functions of anxiety.

Ss chosen from an introductory class in psychology were given the Grice Revision of the Taylor Scale of Manifest Anxiety. High and low scorers were evenly divided as to sex and assigned to threatening or non-threatening instruction groups. Perceptual tasks were then administered. The results indicated that threat induced anxiety modified perceptual processes significantly in the case of tachistoscopic closure, rigidity, and stability. These three functions involve maintaining constancy of a previously established percept in the face of incompatible cues from the environment. Manifest anxiety was related only to the stability test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unconscious memory bias in depression: Perceptual and conceptual processes.

Mood-congruent memory (MCM) bias in depression was investigated using 4 different implicit memory tests. Two of the implicit tests were perceptually driven, and 2 were conceptually driven. Depressed participants and nondepressed controls were assigned to 1 of 4 implicit memory tests after studying positive and negative adjectives. Results showed no MCM bias in the perceptually driven tests. MCM was demonstrated in 1 of the conceptually driven tests, but only for adjectives that were conceptually encoded. Results support the theory that mood-congruent processes in depression are limited to conceptual processing. However, activation of conceptual processes may not be sufficient for demonstrating mood congruency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping in space and time: evidence from the Ternus display

Persistence of the brain and kidney Na+,K(+)-ATPase isozymes to SDS inactivation under different time and temperature conditions of microsome extraction with the detergent was compared. In contrast to enzyme preparations from medulla oblongata the higher sensitivity of the Na+,K(+)-ATPase alpha-isoform (in comparison to alpha +) to SDS inactivation accompanied by its, at least, partial removal from the membrane was found in the preparations from cerebral cortex. This difference in the sensitivity to SDS was eliminated after extraction of microsomes with the detergent at 37 degrees C. The interpretation of the results is based on the assumed differences in the structural organization of the boundary lipids of the neuronal Na+,K(+)-ATPase catalytic subunit isoforms.     

Parallel and serial grouping of image elements in visual perception.

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that Gestalt grouping can indeed occur in parallel in some situations, but we demonstrate that there are also situations where Gestalt grouping becomes serial. We observe substantial time delays when image elements have to be grouped indirectly through a chain of local groupings. We call this chaining process incremental grouping and demonstrate that it can occur for only a single object at a time. We suggest that incremental grouping requires the gradual spread of object-based attention so that eventually all the object's parts become grouped explicitly by an attentional labeling process. Our findings inspire a new incremental grouping theory that relates the parallel, local grouping process to feedforward processing and the serial, incremental grouping process to recurrent processing in the visual cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual and conceptual memory processes in global amnesia.

To determine whether global amnesia reflects a selective deficit in conceptual processing, amnesic and control Ss performed 4 memory tasks that varied processing and retrieval requirements. A study-phase modality (auditory/visual) manipulation validated the nature of processing (perceptual and conceptual) engaged by each task. Amnesic patients were impaired on perceptual and conceptual explicit memory tasks (word-fragment and word-associate cued recall) and were intact on perceptual and conceptual implicit memory tasks (word-fragment completion and word association). These results are consistent with the view that limbic-diencephalic structures damaged in amnesia mediate, in part, processes typically engaged during explicit retrieval. The results are inconsistent, however, with the characterization of that deficit as being one of conceptual processing per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping due to pitch and amplitude in hallucinating schizophrenics

Acquired deficiencies of fibrinogen, antithrombin III and plasminogen are reported in liver disease, and it is known that their plasma levels fluctuate during the day. The aim of this study was to investigate the circadian rhythms of these three factors in chronic liver disease. Five groups of subjects were considered: (A) 15 healthy controls: (B) 15 patients with hepatic alcoholic steatosis; (C) 15 patients with chronic active hepatitis; (D) 15 patients with compensated cirrhosis of the liver, and (E) 15 patients with decompensated cirrhosis with ascites. The levels of fibrinogen, antithrombin III and plasminogen were determined in blood samples drawn in each subject during the span of a day every 3 h starting from midnight. The time-related values were analyzed using the 'population-mean cosinor' method. Groups A and B presented a significant (p < 0.05) circadian rhythm for each variable, group C a significant (p < 0.05) circadian rhythm for fibrinogen and antithrombin III and groups D and E no significant (p > 0.05) circadian rhythms. Statistically significant differences (p < 0.05) were demonstrated among the groups in the mean daily levels of the three variables by ANOVA, the concentrations decreasing with disease severity. These data confirm the existence of a significant diurnal periodicity in the circulating levels of fibrinogen, antithrombin III and plasminogen in controls and suggest that liver disease is associated with progressive circadian modifications in the temporal structure of fibrinogen, antithrombin III and plasminogen, related to the stage of the liver disease. The rhythm derangements may be considered markers of evolution in liver disease.     

Perceptual processes in matching and recognition of complex pictures.

The role of perceptual feature sampling in speeded matching and recognition was explored in 4 experiments. Experiments 1-3 involved a perceptual matching task with pictures of various objects and scenes. In Experiments 2 and 3, same-different judgments were given under time pressure. The main objective of the matching task was to obtain measures of the perceptual processing rates of different object features. Experiment 4 was an old-new recognition experiment, in which the same stimuli as those in the matching task were used. Response signals were used to limit processing time in the recognition task. The results demonstrated that it is possible to predict speeded recognition performance from performance in perceptual matching. A simple stochastic feature-sampling model provides a unified account of the data from the 4 experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual organization of behavior: A hierarchical control model of coordinated action.

Compared the behavior of 4 college students and 2 faculty members (including the present author) with a hierarchical control system model of behavioral organization. Ss varied the position of 2 control handles simultaneously to keep the distance constant between 2 pairs of lines. Three variations on this basic experiment that illustrate some fundamental properties of coordinated action showed (1) how independent actions, compensating for unpredictable and undetectable disturbances, can produce a single behavioral result; (2) how the ability to produce a particular result is maintained when the connection between action and result is changed; and (3) how 2 independent outputs can appear to be related as coordinative structures when one output disturbs a result being controlled by the other. The correlation between the behavior of Ss and the model in all experiments was typically on the order of .99. A detailed examination of the operation of the model demonstrated that actions are structured by perception, not by central commands or equations of constraint. (35 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Contributions of automatic and controlled processes to the analysis of hierarchical structure.

Three experiments provide evidence that 2 mechanisms, 1 automatic and 1 controlled, produce variations in the efficiency with which local and global forms are processed. Targets are identified faster if they appear at the same level (global or local) as the target on the previous trial. M. R. Lamb, B. London, H. M. Pond, and K. A. Whitt (see record 1997-39043-003) provided evidence that the beneficial effect of level repetition is due to an automatic process that is outside voluntary control. In the present experiments, pretrial cues informed participants as to the level of the upcoming target. Valid cues benefited performance, whereas invalid cues harmed performance relative to noninformative neutral cues. This was so even when the relation between the cue and the level it signaled was arbitrary, indicating that the cues initiated voluntary shifts of attention. The benefit associated with level repetition, however, was unaffected by the cues. These data suggest that the benefit of level repetition results from a process that is not subject to voluntary control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual effects on remembering: Recollective processes in picture recognition memory.

In 3 experiments, the effects of perceptual manipulations on recollective experience were tested. In Experiment 1, a picture-superiority effect was obtained for overall recognition and Remember judgments in a picture recognition task. In Experiment 2, size changes of pictorial stimuli across study and test reduced recognition memory and Remember judgments. In Experiment 3, deleterious effects of changes in left–right orientation of pictorial stimuli across study and test were obtained for Remember judgments. An alternate framework that emphasizes a distinctiveness–fluency processing distinction is proposed to account for these findings because they cannot easily be accommodated within the existing account of differences in conceptual and perceptual processing for the 2 categories of recollective experience: Remembering and Knowing, respectively (J. M. Gardiner, 1988; S. Rajaram, 1993). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping of tone sequences by normally hearing and hearing-impaired listeners

This study examined the perceptual grouping of rapid tone sequences for listeners with normal hearing and listeners with unilateral and bilateral cochlear hearing loss. The sequence ABA-ABA- was used, where A and B represent sinusoidal tones bursts (10-ms rise/fall, 80-ms steady state, 20-ms interval between tones) and - represents a silent interval of 120 ms. Tone A was fixed in frequency at 250, 500, 1000, or 2000 Hz. Tone B started with a frequency well above or below that of tone A, and its frequency was swept towards that of tone A so that the frequency separation between them decreased in an exponential manner. Listeners were required to indicate when they could no longer hear the tones A and B as two separate streams, but heard only a single stream with a "gallop" rhythm. This is called the fission boundary. For the normally hearing listeners, the separation between tones A and B at the fission boundary was roughly independent of the frequency of tone A when expressed as the difference in number of ERBs (delta E) between A and B, which is consistent with a recent model of stream segregation [M. W. Beauvois and R. Meddis, J. Acoust. Soc. Am. 99, 2270-2280 (1996)]. For the unilaterally hearing-impaired listeners, there was no consistent difference in the delta E magnitudes across ears, even though the auditory filters were broader in the impaired ears. This is not consistent with the theory of Beauvois and Meddis. The bilaterally hearing-impaired listeners sometimes showed delta E magnitudes within the normal range, and sometimes showed larger than normal delta E magnitudes. The results are discussed in terms of the factors that might influence perceptual stream formation in hearing-impaired listeners.     

Uniform connectedness and grouping in the perceptual organization of hierarchical patterns

The principle of uniform connectedness (S. E. Palmer & I. Rock, 1994) states that connected regions of uniform visual properties correspond to the entry-level units of visual stimuli. The implications of this principle for the perceptual organization of hierarchical patterns were investigated in 3 experiments. Primed matching and visual search were used to examine the microgenesis of organization for patterns that vary in number and relative size of their elements. Results for the few-element patterns showed an initial representation of elements with a weaker representation of global configuration. Grouping of elements into global configuration consolidated with time and involved focused attention. The entry-level units of many-element patterns were global configuration and texture. Individuation of elements occurred later and involved focused attention. These findings are discussed with reference to processes underlying perceptual organization.     

Memory for the Rey-Osterrieth Figure: Perceptual clustering, encoding, and storage.

Administered copy, immediate recall, and delayed recall conditions of the Rey-Osterrieth Complex Figure (ROCF) test to 50 neuropsychiatric patients (aged 23–83 yrs). Measures of copy accuracy, perceptual clustering, encoding, and savings were computed. Perceptual clustering in the copy condition was a better predictor of memory performance than was copy accuracy. An absence of association between the encoding score and the savings score suggests that these indices reflect different cognitive processes. The need to assess both immediate and delayed recall of the ROCF is emphasized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)