Tachistoscopic Task Research Articles

Perceptual and Conceptual Information Processing in Schizophrenia and Depression

Schizophrenic patients (n = 20), depressive patients (n = 20), and normal adults (n = 20) were compared on global vs local analyses of perceptual information using tachistoscopic tasks and on top-down vs bottom-up conceptual processing using card-sort tasks. The schizophrenic group performed more poorly on tasks requiring either global analyses (counting lines when distracting circles were present) or top-down conceptual processing (rule learning) than they did on tasks requiring local analyses (counting heterogeneous lines) or bottom-up processing (attribute identification). The schizophrenic group appeared not to use conceptually guided processing. Normal adults showed the reverse pattern. The depressive group performed similarly to the schizophrenic group on perceptual tasks but closer to the normal group on conceptual tasks, thereby appearing to be less dependent on a particular information-processing strategy. These deficits in organizational strategy may be related to the use of available processing resources as well as the allocation of attention.

The stability of tachistoscopic measures of hemispheric specialization

Two-week test-retest reliabilities were determined for two tachistoscopic tasks, consonant-vowel-consonant trigrams and dot location, in 48 right-handed university students. Both visual field and laterality scores were determined. Analysis of variance showed no significant main effects or interactions of session for either task, indicating stability of mean performance and laterality scores. Likewise, grouping subjects as “high” or “low” by median laterality scores showed concordance across session for both tasks. Test-retest correlations were moderately high for all verbal task measures and for visual field scores for the dot location test. However, laterality indices for dot location showed low stability despite comparable within-session reliabilities of laterality scores for the two tasks. These findings suggest stability of group means and subgroups for verbal and dot location tachistoscopic measures. However, the degree to which individual scores are predictable from one session to the next differs between the two tasks.

Visual information processing after severe closed head injury: effects of forward and backward masking.

Three tachistoscopic tasks were employed to assess whether survivors of severe closed head injury (CHI) exhibit a disturbance of information processing within peripheral and/or central visual pathways. Twelve survivors of severe CHI and 12 individually matched control subjects completed a recognition threshold (no mask) task, a monoptic, forward masking by visual noise task (to assess processing within relatively peripheral pathways), and a dichoptic, backward masking by pattern task (to assess processing within central pathways). For each experimental procedure, the minimum exposure durations required by subjects to identify correctly single consonants and triple consonants were determined. Survivors of severe CHI showed deficits on all three visual tasks. Both groups also had higher threshold durations for the more complex stimuli (triple v single consonants), but differences in threshold were greater in the patients with CHI. The degree of perceptual impairment exhibited by patients with CHI was highly variable and not consistently related to injury characteristics or residual motor or speech and language impairment.

Recognition of Facial Expression in Diverging Socioeconomic Levels

Cerebral organization has been seen to vary in different social or ethnic groups; also, sociocultural retardation is a serious obstacle to development in poorer countries. The ability of the right hemisphere to recognize facial emotions in a tachistoscopic task was tested in university and low-socioeconomic-level subjects. All were male and right-handed. The university students recognized facial emotions projected to their left field-right hemisphere significantly better than with their right field-left hemisphere; the low-socioeconomic-level subjects showed no differences in hemispheric performance. The explanation of laterality as a function of social class may be of importance in dealing with sociocultural retardation.

Dissociations between Word Priming Effects in Normal Subjects and Patients with Memory Disorders: Multiple Memory Systems or Retrieval?

Repetition priming was measured in two different tasks within a single experiment--one in which subjects named briefly (tachistoscopically) presented words, and one requiring naming of visually fragmented/degraded words. Thirteen amnesic patients, 12 patients with Alzheimer's disease (AD), and 15 normal control subjects were tested under 4 experimental conditions involving the factorial combination of two variables: delay of test (10 minutes and 24 hours), and number of prior occurrences of the primed items (1 and 4). The two tasks produced very different patterns of priming effects, despite the fact that common study phases were employed. In one task the priming effect showed no decay and virtually no effect of the number of prior occurrences of the primed items, whereas both these variables affected priming in the other task. The AD patients evidenced impaired priming in both tasks. However, in the degraded-word-naming task the deficit was only apparent under some experimental conditions. The amnesics produced priming effects that in absolute terms were similar to those produced by control subjects. However, when group differences in overall performance level were taken into account in the tachistoscopic task, these patients also showed clear evidence of impaired priming. It is argued that the complex pattern of priming effects obtained is best explained by the characteristics of the retrieval cues provided in the tasks, and, generally, that such characteristics may determine whether or not experimental variables will affect measured priming.

Callosal efficiency is related to sustained attention

The purpose of this study was to determine whether there is a relationship between the efficiency of interhemispheric communication (IHC) and the ability to sustain attention. Children were tested on a vigilance task in which the amount of time between target presentations (interstimulus intervals; ISI) was varied. IHC was assessed by comparing within-field and between-field matches on a tachistoscopic task. Subjects who showed better IHC had faster RTs on the long ISI trials of the vigilance task, suggesting callosal involvement in the ability to sustain attention over a long period of time in the absence of sensory input.

Functional Hemispheric Asymmetry and Belief in ESP: Towards a “Neuropsychology of Belief”

30 right-handed subjects were given a lateralized tachistoscopic lexical-decision task. Subjects' belief in extrasensory perception (ESP) was assessed with a single six-point scale; 16 subjects were designated as believers in ESP and 14 subjects as nonbelievers. Believers in ESP did not exhibit a hemispheric asymmetry for the task while nonbelievers exhibited the expected right visual-field/left-hemisphere dominance documented in the literature. Believers' lack of asymmetry was not caused by an impaired left-hemisphere performance but rather by a significantly enhanced lexical-decision accuracy in the left visual field/right hemisphere compared to nonbelievers. These results are compatible with previous studies indicating a correlation between belief in ESP and a bias for right-hemisphere processing. Moreover, the results are relevant for a discussion of an association between paranormal beliefs and schizotypy: highly schizotypal individuals are not only particularly prone to believe in ESP but are also known to show an attenuation of hemispheric asymmetries in lateralized verbal tasks due to an enhanced contribution of the right hemisphere. We suggest that the neurological basis of delusion-like beliefs may involve a release of right-hemisphere function from left-hemisphere control and sketch the focus of research for a future "neuropsychology of belief."

Sleep wakefulness cycle

Abstract 48 right‐handed subjects performed verbal and spatial hemifield tachistoscopic tasks, half of them in spring and the other half in autumn. Significant differences were detected showing increased right visual field (left hemisphere) advantage in spring and increased left visual field (right hemisphere) advantage in autumn. Results may help to explain the reported seasonal propensity towards elevated mood in spring and towards depressed mood in autumn as related to the relative role of both hemispheres.

Diurnal Type and Hemispheric Asymmetry

Monk and Leng (1986) postulated that Morning-types (M-types) rely more than Evening-types (E-types) on subvocalization strategies, indirectly suggesting a difference in their habitual mode of hemispheric engagement. To evaluate this hypothesis, 48 righthanded women, 24 M-types and 24 age-matched E-types, performed verbal and spatial hemifield tachistoscopic tasks and recorded oral temperature at four separate times of day. Oral temperature curves were larger in amplitude and phase delayed for E-types. Reaction time curves were slower for E-types, without M-E phase differences. Error rate curves showed significant time-of-day effects at left-visual-field verbal tasks for M-types and at right-visual-field spatial tasks for E-types, indicating a selective trend in relying on left hemispheric mode for M-types and on right hemispheric mode for E-types. Implications for circadian oscillatory control are discussed.

Diurnal oscillations in hemispheric performance.

Folkard (1979, 1990) suggested that diurnal changes in performance may reflect a morning-evening decrease in the degree of left-hemisphere dominance. Forty-eight right-handed women performed verbal and spatial hemifield tachistoscopic tasks at four separate times of day. Supporting the above hypotheses, changes in accuracy over the day showed a left-hemisphere advantage at 12:00 and a right-hemisphere advantage at 19:45, whereas changes in speed were symmetrical both in verbal and spatial tasks. These changes occurred only when hemispheres received stimuli in the processing of which they were not specialized, that is, when verbal stimuli appeared at the left visual field and spatial stimuli at the right visual field. Evidence suggesting a separate oscillatory control of the circadian rhythms of left and right-hemisphere activity is discussed.

Effects of processing speed on cerebral asymmetry for left- and right-oriented faces

A free-vision chimeric facial emotion judgment task and a tachistoscopic face-recognition reaction time task were administered to 20 male right-handed subjects. The tachistoscopic task involved judgments of whether a poser in the centrally presented full-face photograph was the same or different poser than in a profile photograph presented in the left or right visual field (LVF, RVF). The free-vision task was that used by J. Levy, W. Heller, M. Banich, and L. Burton ((1983), Brain and Cognition, 2, 404–419) and involved judging which of two chimeric faces appeared happier, in which the two chimeras were mirror images of each other and each chimera consisted of a smiling half-face joined at the midline to a neutral half-face of the same poser. For the tachistoscopic task, subjects were divided into groups of Fast and Slow responders by a median split of the mean reaction times. For the Fast subjects, judgments were faster in the LVF than in the RVF, and there was a significant interaction between visual field and profile direction, such that responses were faster for medially oriented profiles; i.e., LVF responses were faster for right-facing than for left-facing profiles, with the reverse relationship in the RVF. The Slow responders did not show these effects. Only the Fast group showed the bias for choosing the chimera with the smile on the left as happier, and mean response speed and the LVF advantage on the tachistoscopic test correlated with the leftward bias on the free-vision task for all subjects combined. It was suggested that overall response speed on the face-matching task reflected the extent to which specialized and more efficient right hemisphere functions were activated.

Unaware learning versus preserved learning in pharmacologic amnesia: Similarities and differences.

The differences between learning in lorazepam (LOR)--or scopolamine (SCOP)--induced amnesia and learning in unaware drug-free normal subjects were examined. The drugs produced impairment in free recall, but did not affect digit span or word retrieval. In a verbal version, but not a motor version, of the serial reaction time task, the subjects who received SCOP or higher dose LOR showed impairment of sequence-specific learning. Subjects who received placebo had no such impairment. In the stem completion paradigm, higher dose LOR, but not SCOP, impaired performance. In a tachistoscopic word identification task, neither drug interfered with repetition priming. Unaware learning and drug-induced amnesic learning were thus dissociable. These findings disconfirm the hypothesis that unaware learning and drug-induced amnesic learning are analogous.

Are variations among subjects in lateral asymmetry real individual differences or random error in measurement?: Putting variability in its place

The current research investigates sources of variability in subjects' asymmetry scores on commonly used laterality tasks. In particular, subjects' asymmetry scores on four bilateral tachistoscopic tasks and one free-vision task were entered into a principal component analysis (PCA) in order to investigate components that explain the maximum variance of the sample. The results indicate that about half of the variation (45.2%) in asymmetry scores on both tachistoscopic and free-vision tasks is attributable to individual differences in characteristic perceptual asymmetry. The amount of variance explained by this characteristic perceptual asymmetry component is similar in a sample of dextrals and a sample of sinistrals. No significant relation was revealed between individual differences in characteristic perceptual asymmetry and performance on various verbal and spatial cognitive tasks.

Selective activation effects of concurrent verbal and spatial memory loads in left-handed and right-handed adults

Thirty-two left-handed subjects, divided into four groups according to sex and familial sinistrality, and 16 right-handed subjects without familial sinistrality (8 male, 8 female) participated in a tachistoscopic unilateral letter-identification task with concurrent verbal- and spatial-memory loads. Across groups, a significant right visual field advantage for letter-identification was found. In the majority of both left-handed and right-handed subjects, the concurrent verbal-memory load resulted in a selective activation, with the right visual field performance showing improvement. However, the group of left-handed males with a positive family history of sinistrality gave less evidence of selective left-hemispheric activation as a consequence of the verbal-memory load. The concurrent spatial-memory load did not result in a consistent pattern of selective activation.

Asymmetrical Processing of Tachistoscopic Inputs in Undergraduates across Sex, Handedness, Field-Side, and Fixation Instructions

Past studies have indicated that men as well as right-handers show a right-visual field (RVF) advantage for letter recall and a left-visual field (LVF) advantage for letter position recall, suggesting asymmetrical brain organization for these groups. To examine these laterality effects more closely, 96 undergraduates were tested in a tachistoscopic task; they were equally divided by sex and hand dominance. On each of the 48 trials, subjects were required to recall either the letters or respective letter positions within 4 x 4 matrices flashed to the right or left visual field for 100 msec. Subjects further received instructions prior to each trial cueing them as to the field in which the matrix would be positioned (i.e., left, right or neither). Analyses indicated that right-handed men showed the predicted RVF advantage for letters while only right-handed subjects evidenced a LVF advantage for letter positions. Instructions might have contributed to the observed sex difference with letters; this would imply that right-handers exclusively possessed this asymmetrical organization.

Similarity effects in word and pseudoword repetition priming.

Repetition priming refers to the facilitation in the visual identification of a stimulus produced by a recent encounter with that stimulus. In the paradigm used here, subjects performed a naming task in which a sequence of primes was presented; then they performed a tachistoscopic identification task in which the stimuli that were presented varied in their similarity to the primes. The results indicated that repetition priming facilitated the identification of repeated words and pronounceable nonwords that were similar, but not identical, to the recently encountered primes. Moreover, the number of presentations of the primes influenced the amount of facilitation for repeated words but, in contrast to previous findings, had no effect on the amount of facilitation for repeated nonwords or similar words and nonwords. The results are interpreted within a connectionist model of visual word identification.

Cerebral laterality and depression: differences in perceptual asymmetry among diagnostic subtypes.

Examined the influence of diagnostic subtype of depression on perceptual asymmetry for dichotic listening and visual tachistoscopic tasks. A total of 65 unmedicated patients with major depressive disorders and 30 normal controls were tested on a verbal and nonverbal task in each modality. Patients diagnosed according to the DSM-III with melancholia had abnormal perceptual asymmetry for dichotic nonsense syllable and complex tone tasks. In contrast, patients having a nonmelancholic "atypical depression" (reactivity of mood with preserved pleasure capacity and associated features) did not differ from normal controls on these tasks, but had an increased incidence of left handedness. Bipolar depression (history of hypomania) differed from unipolar depression in showing abnormal perceptual asymmetry for a tachistoscopic dot enumeration task. Alterations of perceptual asymmetry in melancholia and bipolar depression were consistent with hypothesized right hemisphere dysfunction.

Cognitive Orientation toward Positive Values in Advanced Participants of the TM and TM-Sidhi Program

The results of two studies, with 15 and 10 college students practicing the Transcendental Meditation (TM) and TM-Sidhi program (ages: M = 28 yr.; M = 29 yr.), and 10 and 9 controls (ages: M = 22.9 yr.; M = 26.2 yr.), respectively, indicate that advanced participants of the TM and TM-Sidhi program may have a cognitive set oriented toward more positive values. Subjects in the TM-TM-Sidhi program exhibited a better recall of positively valued words than the control group in a long-term memory task (45 min.), and they needed fewer exposures to recognize positive than negative words at lower absolute thresholds than the controls in a tachistoscopic experiment. They appraised “significant others” more favorably than the control group on LaForge's Interpersonal Checklist, while self-appraisal was high in both groups. A third study of 11 college students, M age of 22.3 yr., yielded an inverse relationship between differential recognition thresholds for positive and negative affect terms on a tachistoscopic task and the reported experienced intensity of the corresponding affects. This suggests that enhanced perception of certain affect terms may be a function of more frequent experiences of those affects.

What makes you so sure? Effects of epistemic motivations on judgmental confidence

Three experiments examined the effects of motivational variables on the epistemic (or knowledge acquisition) process. The motivations considered were need for cognitive structure and fear of invalidity, and the epistemic phenomena studied were subjective confidence and hypothesis generation. In the first experiment a tachistoscopic task was employed to examine the effects of fear of invalidity upon (1) subjects' initial and final confidence in a hypothesis and (2) shifts in confidence occasioned by successive items of new information. The second experiment replicated and extended the first by investigating the effects of need for structure over and above those of fear of invalidity. The third experiment employed an object recognition task and investigated the process of hypothesis generation assumed to mediate motivational effects on subjective confidence. It was found that both initial confidence and informationally induced confidence shifts were of higher magnitude when subjects' need for structure was high rather than low, and when subjects' fear of invalidity was low rather than high. Furthermore, the number of alternate hypotheses generated was higher under high (versus low) fear of invalidity, and low (vs high) need for structure. The above findings were discussed in reference to Kruglanski's theory of lay epistemology.

Evidence that fixation digits can contribute to visual field asymmetries in lateralized tachistoscopic tasks

Fixation point digits have been widely used in tachistoscopic laterality studies as a simple and convenient means of ensuring unihemispheric projection of stimulus materials to the hemispheres. Previous findings demonstrate that fixation digits do not influence asymmetries in recognition accuracy studies with adult Ss. Present results, comparing four conditions differing in their use of fixation digits, show that in the naming latency paradigm the requirement to remember and report fixation control digits significantly augments RVF superiority. Implications for other latency tasks are discussed.