Laterality for visual-spatial processing in two language-trained chimpanzees (Pan troglodytes).

Most reviews of laterality in nonhuman primates indicate that hemispheric asymmetries, similar to those found in humans, are not evident. With the growing evidence for cognitive processes germane to language in apes, in addition to their phylogenetic similarity to humans, they appear to be useful candidates for studies of laterality. Laterality for visual-spatial processing in 2 language-trained chimpanzees was investigated with a visual half-field paradigm. Initially, Ss were taught to manipulate a joystick that controlled the movement of a cursor on a computer monitor to a central fixation point. Ss were then taught a visual discrimination based on the location of a short line contained within a geometric form. Testing consisted of systematic presentation rates of 15, 122, and 226 ms to the left and right visual fields. For half of the trials, Ss used their left hand to respond and used the right hand for the remaining trials. Accuracy and reaction time (RT) were the dependent measures. One S demonstrated significantly faster RTs to stimuli presented to the left visual field (LVF) regardless of which hand was used to respond. The other S demonstrated a significant LVF bias when using the left hand to respond. Results are discussed in the context of current theories on the evolution of laterality and its relation to linguistic functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploring cerebral asymmetries for the verb generation task.

This study investigated potential right hemisphere involvement in the verb generation task. Six divided visual field experiments explored cerebral asymmetries for word retrieval in the verb generation task as well as in rhyme generation and immediate and delayed word pronunciation. The typical right visual field/left hemisphere (RVF/LH) advantage was observed for pronunciation and rhyme generation. For verb generation, the RVF/LH advantage was obtained only when stimulus items had a single prepotent response and not when there were multiple response alternatives. A semantic priming experiment suggested that activation for less common, related verbs was maintained for a longer time course within the right than within the left hemisphere. The authors suggest that the right hemisphere may play a role in continued activation of semantically related response alternatives in word generation and discuss methodological implications of their findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The contribution of attention to the right visual field advantage for word recognition

Perceptual asymmetries have been explained by structural, attentional bias and attentional advantage models. Structural models focus on asymmetries in the physical access information has to the hemispheres, whereas attentional models focus on asymmetries in the operation of attentional processes. A series of experiments was conducted to assess the contribution of attentional mechanisms to the right visual field (RVF) advantage found for word recognition. Valid, invalid and neutral peripheral cues were presented at a variety of stimulus onset asynchronies to manipulate spatial attention. Results indicated a significant RVF advantage and cueing effect. The effect of the cue was stronger for the left visual field than the RVF. This interaction supports the attentional advantage model which suggests that the left hemisphere requires less attention to process words. The attentional asymmetry is interpreted in terms of the different word processing styles used by the left and right hemispheres. These results have ramifications for the methodology used in divided visual field research and the interpretation of this research.     

Categorical priming in the cerebral hemispheres: automatic in the left hemisphere, postlexical in the right hemisphere?

Automatic and postlexical semantic processing in the cerebral hemispheres was studied by presenting categorically related but nonassociated word pairs (e.g., TABLE-BED) to the left visual field (LVF) or to the right visual field (RVF) in semantic priming experiments. Experiment 1 examined automatic priming across stimulus onset asynchronies (SOAs) of 165 and 750 ms with a low proportion of related pairs and a low nonword ratio, employing a GO-NOGO lexical decision task. In contrast to an earlier view that a larger range of meanings is automatically activated in the right than in the left hemisphere, priming was observed in the RVF/left hemisphere only. SOA did not exert any effects. In Experiment 2, postlexical semantic matching of the prime and the target was encouraged by requiring subjects to respond to both of them at the same time. Now there was priming in the LVF, suggesting that a postlexical matching process works in the right hemisphere. The earlier studies showing a right hemisphere advantage in categorical priming are reinterpreted according to the postlexical right hemisphere hypothesis.     

The use of advance information for motor preparation in Parkinson's disease: effects of cueing and compatibility between warning and imperative stimuli

The ability of 13 Parkinsonian patients and 11 age-matched control subjects to process and use two components of the information given prior to a voluntary movement was studied using reaction time (RT) tasks. This advance information about the direction of a pointing movement was given using a double stimulation paradigm with an auditory warning signal (WS) which occurred prior to a visual imperative signal (IS). The first component of the information was given by the WS at the beginning of each trial, and the second component was the WS-IS compatibility during series of trials. The subjects were tested with three RT paradigms: a cued simple (CS) task, a cued choice (NC) task, and a priming choice (P) task. The results show that the normal subjects used both the lateral cue and the WS-IS compatibility to shorten their RTs, whereas the Parkinsonian patients were able to use the lateral warning signal, but their ability to use the degree of compatibility stimuli was impaired. These data suggest that when dealing with lateral cues in a RT task, Parkinsonian patients have no difficulty in identifying a stimulus and selecting the appropriate response, but that this is no longer so in the case of stimulus compatibility. This impairment may be due to attentional disorders involving a dysfunction affecting the medial premotor system, which includes the basal ganglia and may be responsible for the feedforward movement control deficits associated with Parkinson's disease.     

Mirror-image matching and mental rotation problem solving by baboons (Papio papio): Unilateral input enhances performance.

Three experiments, using a matching-to-sample procedure, were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons. In Exp 1, no significant difference was found in discrimination of mirror-image and asymmetric pattern stimuli. In Exp 2, orientation was assessed within the left (LVF) and right (RVF) visual half-fields. An RVF advantage was found in accuracy for asymmetric patterns, whereas an LVF advantage was found for discrimination of mirror-image stimuli. No significant relation was found between angular disparity of the stimuli and response time. Exp 3 examined the effect of bilateral visual input on accuracy and response time. Significantly lower accuracy and longer response times were found for bilateral compared with unilateral visual input. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of motivation and orientation in sensory preconditioning.

Explored the effect of hunger on sensory preconditioning. Ss were 17 male cats. An appetitive task was used to test for sensory preconditioning effects in order to avoid complications arising from differences of drive state during preconditioning and testing for preconditioning. It was found that hunger facilitated the association between paired auditory and visual stimuli, but not between stimuli presented separately and in random order. Examination of the orientation responses of Ss during preconditioning indicate that the auditory stimulus becomes an arousing cue that signals the onset of the visual stimulus. It is suggested that the orientation responses produced as a consequence of this cue function are responsible for the association of the auditory and visual stimuli. (French summary) (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bihemispheric processing of redundant bilateral lexical information

Cerebral asymmetries in lexical ambiguity resolution were studied. In 2 experiments, targets related to the dominant and subordinate meanings of ambiguous word primes were presented for lexical decision after a 750-ms stimulus onset asynchrony. Experiment 1 compared presentation of target words to the left visual field/right-hemisphere (LVF/RH), to the right visual field/left-hemisphere (RVF/LH), or after redundant bilateral visual field (BVF) presentation. Experiment 2 examined unilateral priming in the absence of a BVF condition. On unilateral trials, priming was observed for dominant meanings in both the LVF/RH and RVF/LH, whereas subordinate priming was obtained only in the RVF/LH. These results suggest a possible role of hemispheric interaction in the availability of ambiguous word meanings. BVF performance evidenced a bilateral redundancy gain and priming that resembled that obtained on RVF/LH trials. Additional BVF analyses were not consistent with a strict race model interpretation and appear to implicate hemispheric cooperation in the bihemisperic processing of lexical information.     

Semantics at a glance: Is the right hemisphere special?

32 undergraduate Ss made an odd/even judgment to a single lateralized logograph, an Arabic numeral. All Ss were right-handed and had normal or corrected-to-normal vision. Stimuli were computer generated; Ss were shown the 8 Arabic numerals used by D. Besner et al (1986). Each S was tested with 1 block for each response hand. Data suggest that the left and right hemispheres are equally efficient at extracting meaning from at least some simple, highly familiar logographs. Particularly notable are the consistent reaction time (RT) differences between the left visual field and right visual field conditions for each response hand condition. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global and local processing in humans (Homo sapiens) and chimpanzees (Pan troglodytes): Use of a visual search task with compound stimuli.

This research assessed the visual processing of the global and local stimulus features in humans and chimpanzees. In Experiment 1, participants were tested with compound stimuli presented in a visual search task. There was an advantage to process the global stimulus level in humans but not in chimpanzees. The global size and the density of the local elements were manipulated in Experiment 2. Humans showed an overall advantage for processing the global shape. Chimpanzees showed an advantage for processing the local shape in the low-density condition but showed no advantage in the dense conditions. In Experiment 3, chimpanzees showed a global advantage when line segments connected the local elements and a local one when the lines were removed. Together, these results suggest a phylogenetic trend in the way compound stimuli are processed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional cues in chronic schizophrenia: Abnormal disengagement of attention.

M. I. Possner's 1980 reaction time (RT) paradigm was used to examine the engagement and disengagement operations of visual selective attention in patients with schizophrenia. In the 1st experiment 14 medicated, chronic schizophrenic Ss (diagnosed by criteria of the Diagnostic and Statistical Manual of Mental Disorders [DSM-I]), and 15 age-matched normal and control Ss made a speeded response to a target preceded by a valid, and invalid, or no cue. Control Ss showed the expected advantage and disadvantage in RT for valid and invalid cues, which suggests intact engagement and disengagement operations. For schizophrenic Ss, valid cues also enhanced RT, but invalid cues did not slow RT. Similar results were found in the 2nd experiment. The failure of unpredictable, invalid cues to inhibit RT in chronic schizophrenia may be related to an abnormality in the disengagement operation of selective attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of stimulus arrangement on hemispheric differences and interhemispheric interaction for processing letter trigrams.

Observers identified consonant-vowel-consonant (CVC) nonsense syllables with the letters arranged horizontally. In each of 2 experiments, there were fewer errors when stimuli were presented to the right visual field (RVF) and left hemisphere (LH) than when stimuli were presented to the left visual field (LVF) and right hemisphere (RH), and the extent to which the number of last-letter errors exceeded the number of first-letter errors was greater on LVF/RH than on RVF/LH trials. When the same stimulus was presented simultaneously to both visual fields (Experiment 2), the qualitative error pattern was very similar to the pattern obtained on LVF/RH trials. These effects replicate results obtained in earlier CVC identification experiments with letters arranged vertically. However. when a single stimulus was presented in the center of the visual field (Experiment 1), so that the first letter of the CVC projected to the LVF/RH and the last letter projected to the RVF/LH, the error pattern was a mixture of the LVF/RH and RVF/LH patterns, as if each hemisphere took the lead for processing the letter it received directly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Familiarity and novelty preferences in infant recognition memory: Implications for information processing.

Investigated the suggestion that young infants show a preference for familiar stimuli that is supplanted by a preference for novel stimuli as they get older and the act of recognition becomes commonplace. In Study 1, 84 Ss (3.5, 4.5, and 6.5 mo old) were tested for visual recognition memory of shapes, using the paired comparison procedure. The 3.5-mo-olds showed a strong preference for the familiar, whereas the older Ss preferred the novel stimulus. In Study 2 with 72 3.5- and 6.5-mo-old Ss, these shifts were found to depend more on familiarization time than on age. Ss of both ages showed a preference for the familiar stimulus after limited exposure to it but shifted to a preference for the novel stimulus after more extended exposure. It is concluded that regardless of age, infants prefer to look at that which is familiar as they begin to process a stimulus; once processing becomes more advanced, their preference shifts to the novel. Findings are therefore contrary to the developmental view investigated. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overt and covert attention and vibrotactile reaction times: Gaze direction, spatial compatibility and hemispatial asymmetry.

Performed 2 vibrotactile reaction time (RT) experiments, using 32 strongly dextral undergraduates to determine if (1) Ss attention toward/away from the operating hand effected RT and (2) there was an interaction with hand-hemispace and spatial compatibility. In Exp I, 16 Ss were administered a 250 Hz vibratory stimulus to the forefinger of a hand and were required to depress a switch as soon as the stimulus was felt. Hemispace of the stimulated hand was varied and head turns were recorded. In Exp II, 16 Ss were presented with stimuli to the left and the right hand and Ss looked at 1 hand for a block of trials. Results suggest that vibrotactile asymmetries may stem from differences in ability to hold covert attention in a number of spatial locations. It is suggested that overt and covert attention play different mediating roles in performance asymmetries, both at the hemispatial level and in classical anatomical connectivity paradigms of visual field and ear of entry. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus-response compatibility and automatic response activation: evidence from psychophysiological studies

Effects of dimensional overlap between stimuli and responses on partial response activation were investigated within a priming paradigm with the help of event-related potentials. The likely position of a target stimulus (requiring a left or a right reaction) was indicated by an arrow precue. To test whether automatic response activation processes are triggered by the cue, the lateralized readiness potential was computed. It was found that responses congruent to the direction of the cue were activated about 200 ms after cue onset. This early process was unaffected by specific cue-response contingencies and was completely missing when a nonspatial (color) cue was used. A second response activation phase was observed, which was partially controlled by specific response instructions and subjective expectancies. It is concluded that when stimuli and responses overlap with respect to spatial attributes, automatic response activation process are triggered, which may later be replaced by the activation of an expected response.     

Escape conditioning in wild and domestic Norway rats.

Tested 16 female wild (lab-reared) and 16 female domestic Norway rats for acquisition of a conditioned escape response. To escape from an aversive stimulus (air blasts) Ss were required to open 1 of 8 doors (simulated burrow entrances) on the presence of a visual cue. Stocks did not differ in the rate of conditioning. Wild Ss exhibited significantly shorter latencies for ambulation and escape than domestic Ss. Removal and reinstatement of the visual cue following acquisition confirmed that the Ss used the cue for orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and semantic processing in reading Kanji.

A. Nakagawa (see record 1992-15549-001) showed hemispheric asymmetries during semantic processing of single English words. The right hemisphere passively maintained both strong and weak associations, whereas the left hemisphere maintained only strong associations when Ss were left free to attend. The present study extends the methodology to the study of Kanji characters. Contrary to the study of English characters, there was a general right-hemisphere advantage in single-character Kanji words. A study using a visual cue to direct attention suggested that the right-hemisphere advantage of Kanji was due to better representation of visual features by the posterior right hemisphere. However, the pattern of semantic priming found in English was replicated. Semantic analysis, mediated by more anterior systems, appears similar in the 2 languages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A violation of pure insertion: Mental rotation and choice reaction time.

Six experiments tested the assumption that the mental rotation process is purely inserted into a mirror–normal discrimination task. In Exp 1, Ss took significantly longer to respond to upright characters in blocks containing rotated stimuli than in blocks containing only upright stimuli. Exps 2 and 3 showed that this rotational uncertainty effect was not caused by the need to determine stimulus orientation, and Exp 4 showed that it was independent of the visual quality of the stimulus. Exp 5 showed that the effect was greatly reduced when Ss performed a go–no-go task rather than choice reaction time (RT), and Exp 6 showed that it was independent of the complexity of the response required in the choice task. Results suggest that response selection in a choice RT mirror–normal discrimination task is altered when mental rotation is added, violating the assumption of pure insertion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Persistence of negative priming: II. Evidence for episodic trace retrieval.

Responses to recently ignored stimuli may be slower or less accurate than to new stimuli. This negative priming effect decays over time when delay is randomized within Ss, but not when delay varies between Ss. In Exp 1, response–stimulus intervals (RSI) of 500 and 4,000 msec were randomized within Ss in a target localization task. Negative priming of ignored locations diminished with longer delay. However, no significant decay was obtained when RSI and the preceding RSI were equal. Similar results were obtained when RSI and preceding RSI were deliberately confounded by blocking (Exp 2). Negative priming appears to depend on temporal discriminability of the priming episode. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing of form stimuli presented unilaterally in humans, chimpanzees (Pan troglodytes), and monkeys (Macaca mulatta).

Visual forms were unilaterally presented using a video-task paradigm to 10 humans, 3 chimpanzees, and 2 rhesus monkeys to determine whether hemispheric advantages existed in the processing of these stimuli. Both accuracy and reaction time served as dependent measures. For the chimpanzees, a significant right hemisphere advantage was found within the first 3 test sessions. The humans and monkeys failed to show a hemispheric advantage as determined by accuracy scores. Analysis of reaction time data revealed a significant left hemisphere advantage for the monkeys. A Visual Half-Field?×?Block interaction was found for the chimpanzees, with a significant left visual field advantage in Block 2, whereas a right visual field advantage was found in Block 4. In the human subjects, a left visual field advantage was found in Block 3 when they used their right hands to respond. The results are discussed in relation to recent reports of hemispheric advantages for nonhuman primates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)