Effects of variations in the preparatory interval on the reaction time of retardates and normals.

Conducted 2 studies to evaluate the effects, on simple RTs, of warning signal duration (WSD) and preparatory interval (PI) with normal and mentally retarded Ss. In Exp. I PIs of 2, 4, 8, and 12 sec. were presented in an unpredictable sequence. For 1/2 of the Ss the warning signal remained on throughout the entire PI (filled condition) and for the remainder of the Ss, the warning signal was present for only 1.5 sec. of the PI. Significant effects of intelligence, PI, and WSD were found. The interaction Intelligence * PI was also significant. The unfilled condition resulted from produced faster RTs for both normals and retardates. The interaction resulted from the particularly poor performance of the retardates at the short PIs. Exp. II employed a 1.5 sec WSD with PIs of 2, 4, 8, 16, and 32 sec. An interaction was found involving intelligence and PI. Results are discussed in terms of temporal uncertainty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Warned reaction times of manic-depressive patients with and without lithium.

To assess the performance of manic-depressive patients and normal controls, a warned reaction time task was employed with 20 normal control Ss and 36 manic-depressive outpatients in the free, hypomanic, and depressed states, with and without maintenance levels of lithium carbonate. A warning light appeared at a variable interval preceding a light to which the S responded with a keypress. All Ss received both a regular and an irregular series with warning intervals of 1, 2, 4, 8, and 16 sec. In the regular series, blocks of intervals followed every other interval equally often. Manic-depressives were uniformly slower than controls in both series at all intervals. Maintenance levels of lithium facilitated reaction times particularly at the longer intervals in the irregular series. Depressive as well as hypomanic states tended to yield faster reaction times than the free state. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Boundary extension: Fundamental aspect of pictorial representation or encoding artifact?

Viewers remember seeing more of a scene than was actually depicted in a photograph, a phenomenon called boundary extension (H. Intraub & M. Richardson, 1989). The authors tested whether prior warning would eliminate this distortion, by having 81 Ss view 12 photographs of simple scenes for 15 sec each after receiving 1 of 3 encoding instructions. All Ss were told to remember each picture in detail. Control Ss received no additional information. Test-informed Ss received prior warning about the type of tests. Demo Ss experienced a demonstration of the phenomenon and were instructed to guard against it. After presentation, a drawing task and a boundary recognition test were administered. Prior warning sometimes reduced, but never eliminated, boundary extension. It is suggested that the phenomenon reflects activation of scene expectations during perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reward value of brain stimulation is inversely related to uncertainty about its onset.

Conducted 2 experiments with a total of 9 male Sprague-Dawley rats previously shown to be self-stimulators. Ss were presented with .5-sec trains of electrical stimulation of the brain (ESB) on a response-in-dependent variable-interval 1-min schedule in a shuttle box. When offered a choice between brief and long warning signals prior to ESB, Ss preferred signal durations in the range of .5-3 sec. over longer durations. Furthermore, some Ss did not prefer ESB to no ESB unless ESB was preceded by a brief warning signal. It is concluded that the reinforcing value of ESB is inversely related to temporal uncertainty about its onset. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of speed of exposure and difficulty of discrimination on visual recognition of retarded readers.

Administered a tachistoscopic recognition task to 36 retarded and 36 normal 6-7 yr old readers to determine whether retarded Ss' visual-perceptual deficit was a function of speed of exposure and/or difficulty of discriminating alternatives on response cards. 3 time exposures were employed, and there were 2 sets of response cards. All cells in the factorial design were independent, and the same stimuli were presented tachistoscopically to all Ss. It was found that speed of exposure, not difficulty of response cards, differentiated between retarded and normal Ss. At the faster exposures of 10 msec and 1 sec, retarded Ss performed significantly less well than normals, but they equaled the performance of normals at the slower exposure of 5 sec. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus exposure time as a factor in serial learning in an aged sample.

Stimulus exposure and learning in old (O) and young (Y) Ss was investigated. Lists of 8 words equated for size, association value, and structure were used in a serial rote learning task with a 1-sec. interword interval and a 45-sec. intertrial interval. 3 groups of Y (M = 37.3 yr.) and O (M = 66.5 yr.) men received exposure times of 4, 6, or 8 sec., comprising a 3 X 2 A of V design (N = 81). WAIS Vocabulary scores served as a control. Conclusions are: (a) Y Ss learned better than O (p     

Sensibilité et diagnosticité de la mesure de la charge mentale par la tache secondaire de frappe cadencée.

Studied the sensitivity of finger tapping performance as a measure of the mental workload produced by a concurrent memory task. Ss were 8 normal male and female adults (aged 22–39 yrs). Over 4 experimental sessions, Ss were asked to complete 240 series of 13 finger taps at a rate of 1 tap every 2 sec. The concurrent primary task required Ss to search for a target item (presented after each tap) in a 3-digit set memorized before each series of taps. Processing load was varied by including letter targets among positive and negative digit targets. Intertap intervals for letter targets, positive digit targets, and negative digit targets were compared. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampus, time, and memory.

Five experiments determined the effects of hippocampal damage on timing and the memory for temporal events. Norway rats (N?=?20) were trained to discriminate between auditory signals that differed in both duration (2 or 8 sec) and rate (2 or 16 cycles/sec). After Ss acquired the discrimination, signals with intermediate durations and rates were presented. Ss then received either fimbria-fornix lesions or control operations. Postoperatively, the accuracy of duration and rate discriminations as measured by the difference limen (DL) was unaffected by the lesion, but the point of subjective equality was shifted to a shorter duration and a slower rate by the lesion. Both Ss with lesions and Ss with control operations showed cross-modal transfer of duration and rate from the auditory signals used in training to visual signals. When a 5-sec delay was imposed between the end of a signal and the opportunity to respond, lesioned Ss were selectively impaired by the addition of the delay as measured by an increase in the DL. When a peak procedure was employed, the maximum response rate of controls was approximately at the time of scheduled reinforcement (20 sec), but the maximum response rate of lesioned Ss was earlier than the time of reinforcement. When a 5-sec gap was imposed in the signal, controls summed the signal durations before and after the gap, whereas lesioned Ss showed no retention of the signal duration prior to the gap. Lesions impaired spatial working memory in an 8-arm radial maze. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual specificity effects on word stem completion: Beyond transfer appropriate processing?

Explored the determinants of perceptual specificity effects (PSEs) in visual word-stem completion. 256 undergraduates participated in 4 experiments. In Exp 1, Ss completed a stem completion task after a number-search task in study-condition and -case phases. Ss were assessed for their awareness of the study-task relationship and compliance with instructions. In Exp 2, retrieval instructions and study task were manipulated within Ss and between 4 study-test blocks. Ss in Exp 3 completed study-test blocks with unintentional test instructions as in Exp 2. In Exp 4, retention interval, and study-task and -case were manipulated within the Ss. In Exp 1, PSEs on the stem completion task depended on perceptual encoding when Ss' awareness of the study-test relationship was limited. In Exps 2–4, these effects depended on semantic encoding. PSEs after short retention intervals were independent of encoding task. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of task complexity and practice on performance after loss of sleep.

An experiment was conducted to assess the effects of degrees of task complexity and practice on performance after loss of sleep. The Ss were automatically presented every 7 sec. for 23 min., with cards containing 6 symbols. A symbol had to be chosen on the basis of certain rules. Some cards required 1 rule, some 2, some 3, and some 4. Group 1 was practiced after normal sleep and tested after 22 and 46 hr. without sleep. Group 2 was tested without sleep and without previous practice. Group 3 was practiced and tested after normal sleep. Loss of sleep had a greater effect after practice, but no clear differences emerged between the different levels of task complexity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced discriminated bar-press avoidance in the rat through appetitive preconditioning.

In 2 experiments with 57 male albino rats, an appetitive preconditioning procedure produced superior performance on a discriminated bar-press avoidance task. The technique was designed to minimize the number of shocks received early in training and consisted primarily of rewarding Ss with food pellets for an avoidance response in addition to terminating the warning stimulus. Ss so preconditioned were found to achieve sustained, high levels of avoidance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Saccadic eye movements of children and adults to double-step stimuli.

Investigated the programming and reprogramming of oculomotor responses to double-step and single-step targets in Exp I with 5 college students, 5 5–6 yr olds, and 7 8–10 yr olds. Independent variables were intertarget interval (50, 100, 150, and 200 msec) and target location. The number of trials on which a saccade was made to both 1st and 2nd targets increased with age and intertarget interval, but the 2 factors did not interact. On trials where responses were made only to the 2nd target, children responded slower than adults but showed generally similar patterns of response latencies. In Exp II, a warning signal was presented 0, 100, or 300 msec prior to the 1st target. For 18 college students, the 100- and 300-msec warning intervals reduced the latency of single-step responses and the 1st saccade of double-step responses, whereas only the 300-msec warning interval was similarly effective with 15 children. All Ss exhibited amplitude transition functions, indicating that the modifiability of saccadic programming is basically similar for adults and children. A comparison of simultaneous programming characteristics suggested possible age differences. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive penetrability of syntactic priming in Broca's aphasia.

Agrammatic Broca's aphasia has been explained as an impairment of automatic syntactic processes. The present study investigated whether controlled processes play a role in agrammatics' handling of syntactic information. Agrammatic patients and normal controls performed a cross-modal priming task with sentence fragments and visual targets forming either grammatical or ungrammatical pairs. In Exp 1, Ss of both groups were instructed to ignore the auditory prime. The grammaticality effect observed in a previous study disappeared for the aphasic Ss but not for normal controls. Exp 2 demonstrated that for normal controls, the grammaticality effect was present even with a larger prime-target interval. These findings indicate that although automatic parsing routines in normal Ss are impervious to strategic effects, agrammatic Broca patients appear to use syntactic information in a controlled fashion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal use of an internal clock.

Used time-discrimination procedures with male albino Charles River rats to determine if light and sound are timed by the same internal clock and if measured durations of light and sound are stored in the same memory. Exp I used a choice procedure and a cross-modal transfer-of-training design. There was transfer of the time discrimination across modalities: To some extent, Ss treated the new signal (sound) as if it were the old signal (light). Exp II (6 experienced Ss) showed that changing the time of food during light (or sound) changed peak time during sound (or light). In Exps III and IV, intervals of light (or sound) were followed by intervals of sound (or light). The interval of light decreased the peak time measured from the start of the interval of sound, whether the 2 intervals were adjacent or separated by 5 sec. The longer the 1st interval, the greater the decrease. Findings suggest that measured durations of light and sound are stored by the same memory and that light and sound are timed by the same clock. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual coherence of speech: Stability of silence-cued stop consonants.

Five experiments, with 25 undergraduates, examined the perceptual stability of stop consonants cued by silence alone, as when [s]?+?silence?+?[l?t] is perceived as splat. Following a replication of this perceptual integration phenomenon, attempts were made to block it by instructing Ss to disregard the initial [s] and to focus instead on the onset of the following signal, which was varied from [pl?t] to [l?t]. However, these instructions had little effect at short silence durations, and they reduced stop percepts for only 2 Ss at longer silence durations. That is, Ss were generally unable to voluntarily dissociate the [s] noise from the following signal and thus to perceive the silent interval as silence rather than as a carrier of phonetic information. A low-uncertainty paradigm facilitated the task somewhat. However, when the [s] frication was replaced with broadband noise, Ss had no trouble in the selective-attention task, except at silence durations of less than 40 msec. Results support the hypothesis that perceptual integration of speech components, including silence, is a largely obligatory perceptual function driven by the listener's tacit knowledge of phonetic regularities. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of biological and social motivation on schizophrenic reaction time.

Reaction times of schizophrenic and normal Ss were determined under instructions to respond as fast as possible to a buzzer signal. Half of the Ss were retested immediately under the same conditions, while the other half were shocked on the responding finger simultaneously with the buzzer. Schizophrenics' RTs improved significantly under shock conditions. Disturbances in schizophrenic RT are "partially accounted for by defective social motivation and… a biological deficit may be involved in the reactions of more chronic schizophrenics." 21 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preservation of cross-modal transfer of a rate discrimination in the bushbaby (Galogo senegalensis) with lesions of posterior neocortex.

Assessed the effect of lesions of posterior neocortex, using a test method that permits the demonstration of cross-modal transfer in intact bushbabies. Eight Ss were trained to discriminate light flashes of 18/sec and 3/sec in a go-no-go shock avoidance task. On completion of training, 4 Ss received lesions of posterior neocortex by aspiration. After 6 wks both lesion and intact Ss were returned to training in the visual discrimination. On the day following criterion performance on the visual test, auditory clicks of the same rate and contingencies were substituted and maintained to criterion. All 8 Ss demonstrated rapid transfer, and the lesion Ss were not retarded as compared with intact Ss. The cross-modal transfer of a specific rate discrimination was thus preserved in the absence of posterior intersensory neocortex. Results are discussed in terms of a hypothetical subcortical system capable of the amodal coding of simple stimulus dimensions. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vigilance performance as a function of interpolated rest.

2 experiments were performed on the effects of interpolated rest upon monitoring performance at both high and low signal rates. Experiment I employed 2 groups of 20 Ss each; Experiment II employed 2 groups of 10 Ss each. One group of Ss worked on a light monitoring task for 3 30-min. periods separated by 10-min. rest periods. The 2nd group worked continuously for 90 min. on the same task. Experiment I employed 24 signals/hr.; Experiment II employed 6 signals/hr. The results indicated a highly significant facilitation of detection performance as a result of interpolated rest at both signal rates and demonstrate the effectiveness of relatively brief rest intervals in maintaining high performance even with low signal rates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term retention of a complex operant in pigeons.

Examined the effects of a 60-day retention interval on sequence performance when White Carneaux pigeons were required to peck each of 2 keys 4 times in any order for reinforcement. In Exp I, with 20 Ss, it was shown that if the retention interval contained no interpolated experimental experience, it had no effect on sequence performance. If Ss pecked a key for food on a VI schedule during the retention interval, sequence disruption occurred. In Exp II, with 10 Ss, it was found that variations in the location and color of a key pecked during VI had no effect on disruption. In Exp III, with 20 Ss, it was found that disruption did not occur when Ss were simply placed in the experimental chamber during the retention interval, or given response-independent food, or given VI reinforcement for hopping on a foot treadle. In Exp IV, with 15 Ss, disruption was found even when interpolated keypeck training demanded a temporal pattern different from what had occurred on the sequence task. In Exp V, with 5 Ss, it was demonstrated that disruption could be prevented if Ss were exposed to an alternation of the sequence and VI procedures during initial acquisition. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive factors in differential conditioning of the GSR: Use of a reaction time task as the UCS with normals and schizophrenics.

22 normals and 22 schizophrenics underwent differential conditioning of the GSR, using 8-sec tones of differing frequencies as the CSs, an 8-sec CS-UCS interval, and a UCS comprised of an RT task signaled by a low-intensity light. Both intertrial reports and postconditioning interviews were obtained. 12 Ss in the normal group verbalized the CS relations accurately, compared to 3 Ss in the schizophrenic group. The normal group showed significant GSR differentiation, though conditioning was limited to the group of accurately verbalizing Ss. No evidence for conditioning was obtained in the schizophrenic group. Normal Ss had faster RTs than schizophrenic Ss. The RT of accurately verbalizing normals was shorter than that of inaccurately verbalizing normals, and the degree of GSR differentiation was significantly correlated with RT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)