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T N Tombaugh

Publications and source records attributed to T N Tombaugh.

At least 19 recordsLinked to original sources
PubMed2004

The effects of list difficulty and modality of presentation on a computerized version of the Paced Serial Addition Test (PSAT).

The Paced Serial Addition Test (PSAT) presents a series of digits at different speeds with the requirement that the two most recent numbers be added together. Although the PSAT is a relatively difficult test, its level of difficulty may be decreased by changing the number list to make the answers simpler and by presenting the digits visually rather than aurally. In view of this, the present experiment varied both task difficulty (easy vs. hard) and mode of presentation (visual vs. auditory). Task difficulty was manipulated by using two different lists composed of single digits whose answers ranged between 2 and 10 (easy) or 2 and 18 (hard). All stimuli were presented by computer which permitted measurement of response latencies, as well as correctness of responding. The results showed that mode of presentation, but not task difficulty, produced highly significant effects. Additional evidence showed that the ability to compute answers to simple addition problems must be considered as a modulator variable. However, an individual's basic arithmetic ability is not as critical as the modality in which a stimulus is presented. The lower performance associated with the auditory version (i.e., PASAT) was interpreted as an interference effect caused by both the stimulus and the response occurring in a single auditory information processing channel. This interpretation suggests that the PASAT's well documented sensitivity to traumatic brain injury (TBI) may be due, at least in part, to an increased susceptibility to interference effects rather than attributable solely to a decreased rate of information processing.

Acoustic Stimulation↗
PubMed2004

The Adjusting-Paced Serial Addition Test (Adjusting-PSAT): thresholds for speed of information processing as a function of stimulus modality and problem complexity.

A modified computer version of the PASAT (Adjusting-PSAT; ) is described that measures speed of information processing and working memory by means of a temporal threshold rather than number of correct responses. This is accomplished by making the duration of the interval between numbers depend on the correctness of responding-a correct response decreases the interval between digits and an incorrect response increases the interval. Modality of presentation (visual and auditory) was factorially combined with problem difficulty (answers between 2-10 or 2-18). Performance of 60 healthy student volunteers on the Adjusting-PSAT was compared to that obtained on several traditional neuropsychological measures (Digit Span, Trail Making Test, and Symbol Digit Modality Test) and on a test of basic addition skills. The visual version of the test produced a lower threshold than did the auditory version, but problem difficulty did not produce a significant effect. Of the neuropsychological tests, Trails-B (TMT-B) was most highly correlated with thresholds. However, regression analyses revealed that math ability accounted for more variance than did TMT-B. The clinical implications of these finding are discussed.

Acoustic Stimulation↗
PubMed2001

Rates of forgetting on three measures of verbal learning using retention intervals ranging from 20 min to 62 days.

Previous research has examined age effects in rates of forgetting at short delay intervals of 20-30 min. The present study examined age effects in three verbal memory tasks at longer delay intervals of up to 62 days. Study participants consisted of 371 community-dwelling men and women comprising three age groups 20-39, 40-59, and 60-79 years. Age differences in acquisition and 20-min delayed recall were found on each of the memory tasks (paragraph, word list, and word pairs). However, all age groups showed equivalent rates of forgetting after this short delay interval. When participants were required to retain information for longer delay intervals (i.e., 1-62 days), increasing age was associated with faster rates of forgetting for day 1, but not over longer delay intervals. Age differences in rates of forgetting for longer delay intervals and the facilitating effects of prompted recall are discussed in terms of encoding and storage versus retrieval processes.

Adult↗
PubMed2001

Depression and the Test of Memory Malingering.

Research on the Test of Memory Malingering (TOMM) [Tombaugh, T. N., 1996. The Test of Memory Malingering. Toronto, Canada: Multi-Health Systems], has consistently shown that it is sensitive to exaggerated or deliberate faking of memory impairment, but it is relatively unaffected by a wide variety of neurological impairments causing genuine memory dysfunction. However, there is little research on the effects that affective disorders have on the TOMM. The current study examined how inpatients diagnosed with major depression performed on the TOMM. Results show that the TOMM is unaffected by affective state. These results, combined with those from previous research, provide converging evidence that performance on the TOMM below a cutoff score of 45 cannot be attributable to depression, neurological impairment, age or education.

Journal Article↗
PubMed1999

Normative data stratified by age and education for two measures of verbal fluency: FAS and animal naming.

Normative data stratified by three levels of age (16-59, 60-79, and 80-95 years) and three levels of education (0-8, 9-12, and 13-21 years) are presented for phonemic verbal fluency (FAS) and categorical verbal fluency (Animal Naming). The normative sample, aged 16 to 95 years, consisted of 1,300 cognitively intact individuals who resided in the community. Years of education ranged from 0 to 21. The total number of words in 1 minute for each of the letters F, A, and S was correlated r =.52 with the number of animal names generated in 1 minute. Regression analyses showed that FAS was more sensitive to the effects of education (18.6% of the variance) than age (11.0% of the variance). The opposite relationship occurred for Animal Naming, where age accounted for 23.4% of the variance and education accounted only for 13.6%. Gender accounted for less than 1% of variance for FAS and Animal Naming. The clinical utility of these norms is discussed.

Journal Article↗
PubMed1997

The 60-item Boston Naming Test: norms for cognitively intact adults aged 25 to 88 years.

Age- and education-stratified norms on the 60-item Boston Naming Test (BNT) are presented for 219 cognitively intact adults aged 25-88 years. The sample size, age range, and education levels of this sample represent an improvement over currently available norms. Eight short forms of the BNT are compared with the 60-item BNT. Frequency of errors for individual BNT items and the distribution of incorrect responses over seven different categories of errors are discussed. Finally, specific probes to overcome difficulties with ambiguous items are suggested.

Adult↗
PubMed1992

Effects of age on the Rey-Osterrieth and Taylor complex figures: test-retest data using an intentional learning paradigm.

The degree to which the Rey-Osterrieth and Taylor complex figures provide equivalent measures of visual memory, and the effects of age on figure comparability were examined in two experiments. Both experiments employed a multiple-trial, intentional learning procedure wherein each figure was administered twice in a counterbalanced sequence to subjects aged 20 to 80 years. In Experiment 1, a constant 60-s exposure duration was used; in Experiment 2, a self-pacing procedure was employed where the exposure duration was individually determined. The results from both experiments showed that the Taylor figure was easier to learn than the Rey-Osterrieth figure, indicating that the two figures are not equivalent for testing memory. These results were supported by subjective judgements on the relative difficulty to learn and remember each figure. Finally, younger (20-59 years) subjects performed at a higher level than older (60-80 years) subjects on both figures. Recommendations and possible alternatives are suggested regarding the use of the figures in both constructional and visuo-spatial memory test-retest situations.

Adult↗
PubMed1992

The mini-mental state examination: a comprehensive review.

OBJECTIVE: The purpose of this paper is to provide a comprehensive review of information accumulated over the past 26 years regarding the psychometric properties and utility of the Mini-Mental State Examination (MMSE). PARTICIPANTS: The reviewed studies assessed a wide variety of subjects, ranging from cognitively intact community residents to those with severe cognitive impairment associated with various types of dementing illnesses. MAIN OUTCOME MEASURES: The validity of the MMSE was compared against a variety of gold standards, including DSM-III-R and NINCDS-ADRDA criteria, clinical diagnoses, Activities of Daily Living measures, and other tests that putatively identify and measure cognitive impairment. RESULTS: Reliability and construct validity were judged to be satisfactory. Measures of criterion validity showed high levels of sensitivity for moderate-to-severe cognitive impairment and lower levels for mild degrees of impairment. Content analyses revealed the MMSE was highly verbal, and not all items were equally sensitive to cognitive impairment. Items measuring language were judged to be relatively easy and lacked utility for identifying mild language deficits. Overall, MMSE scores were affected by age, education, and cultural background, but not gender. CONCLUSIONS: In general, the MMSE fulfilled its original goal of providing a brief screening test that quantitatively assesses the severity of cognitive impairment and documents cognitive changes occurring over time. The MMSE should not, by itself, be used as a diagnostic tool to identify dementia. Suggestions for the clinical use of the MMSE are made.

Activities of Daily Living↗
PubMed1991

Four studies comparing the Rey-Osterrieth and Taylor complex figures.

The ability of the Rey-Osterrieth (R-O) and Taylor complex figures to produce equivalent scores on both constructional and memory tasks was examined in four studies. While the two figures yielded equivalent copy scores, the Taylor figure produced significantly higher scores on memory tests. This latter relationship was observed with three different retention conditions (immediate, 20-min, and 1-month recall), two types of learning paradigms (incidental and intentional), and two scoring systems (itemized and clinical neuropsychological). The failure to obtain equivalent recall scores cautions against using the R-O and Taylor as companion figures to evaluate normal recovery and treatment effectiveness on mnemonic processes. The relative merits of using an intentional rather than an incidental procedure to administer the figures in test-retest situations are discussed.

Adult↗
PubMed1983

Failure to replicate the dorsal bundle extinction effect: telencephalic norepinephrine depletion does not reliably increase resistance to extinction but does augment gustatory neophobia.

Depletion of telencephalic noradrenaline (Ne), caused by lesion of the dorsal tegmental bundle, has been reported to increase persistence of non-reinforced responding in various operant tasks. This has been referred to as the dorsal bundle extinction effect (DBEE). In an effort to reproduce this effect, rats receiving 6-hydroxydopamine lesions of the dorsal Ne bundle (DB-6-OHDA) were compared to controls during extinction of a continuous food rewarded (CRF) lever-press response. While the lesion group showed an increase in responding during initial extinction, no significant difference in resistance to extinction using a 2-min non-response criterion was obtained. Moreover, no differences in reinforced response rates were observed with CRF, fixed ratio (FR-15, FR-30, FR-60) or variable interval (VI-30, VI-60, VI-120 s) schedules of reinforcement. In order to test the hypothesis that the DBEE is dependent on time of behavioral testing after surgery, subsequent experiments were performed where rats began CRF operant training 5, 17, 31 or 110 days post-lesion. No differences in resistance to extinction were observed between lesion and control rats at any post-lesion interval. Neonatal treatment with 6-OHDA which permanently lesions forebrain Ne terminals also failed to prolong extinction. Finally, when both DB-6-OHDA and neonatal rats were given a choice between water and saccharin the lesioned animals exhibited a neophobic reaction whereby they drank significantly less saccharin. We conclude that while the DBEE is not a reliably reproducible phenomenon other effects of forebrain Ne lesions, such as neophobia, appear to be robust.

Afferent Pathways↗
PubMed1983

Failure of pimozide to disrupt the acquisition of light-dark and spatial discrimination problems.

The effects of pimozide, a dopamine (DA) receptor blocker, on associative learning was examined using two appetitively motivated choice paradigms. In Experiment I, low to moderate doses of pimozide (0.125, 0.25 mg/kg) were not found to disrupt the acquisition of a two bar simultaneous discrimination task. However, with continued testing, progressive deficits in response accuracy were observed in rats pretreated with 0.25 mg/kg pimozide. When subsequently tested drug-free these animals demonstrated a rapid and marked improvement in performance. Experiment II used a spatial discrimination task (T-maze) requiring a natural response (running) with minimal response demands (short stem and arms). Rats pretreated with 0.25, 0.50, and 1.0 mg/kg pimozide showed comparable levels of acquisition and maintained discriminated performance relative to vehicle controls. Similar results were obtained when the reinforced (S+) and nonreinforced (S-) stimuli were reversed. Moreover, animals receiving 2.0 mg/kg pimozide and not rendered cataleptic also demonstrated acquisition of both the initial discrimination and its reversal. It was concluded that rats pretreated with pimozide are able to acquire the significance of environmental stimuli and direct their responding accordingly if they are motorically capable of emitting the required response.

Animals↗
PubMed1983

Alteration of exploration and the response to food associated cues after treatment with pimozide.

A series of experiments assessed the effects of pimozide on spontaneous alternation in a Y- and 8-arm radial maze, and on approach to food or cues that had previously been associated with food. Mice treated with pimozide (0.2, 0.4 and 0.8 mg/kg) displayed a dose dependent reduction of alternation performance, without engendering a perseverative tendency and apparently without affecting the course of habituation. When food deprived mice entered an arm of the maze that was baited with a food pellet they consumed the food and remained in the vicinity of the food cup. Moreover, upon retesting in the non-drug state mice still exhibited a preference for cues that had been associated with food. It seems that although pimozide at the doses tested produced a haphazard pattern of exploration, the drug did not alter the rewarding value of secondary reinforcers. Contrary to an anhedonic hypothesis, it is suggested that higher doses of pimozide may actually increase, rather than decrease, the saliency of biologically significant stimuli.

Animals↗
PubMed1982

Failure to obtain functional equivalence between dopamine receptor blockade and extinction: evidence supporting a sensory-motor conditioning hypothesis.

The effects of pimozide were tested in a discrete trial paradigm. Following 8 days of continuous reinforcement training with a retractable bar, subjects were divided into 3 groups: Vehicle-Extinction; Pimozide-Extinction and Pimozide-Reinforcement. Pimozide rats received 1 mg/kg of drug 4 hours prior to test. On each of 3 test days reinforcement continued to be delivered on a continuous reinforcement schedule for the Pimozide-Reinforcement Group whereas it was no longer delivered for the other two groups. Each test day was separated by 4 drug-free days. The Pimozide-Reinforcement Group showed the least response suppression, followed by the Vehicle-Extinction and Pimozide-Extinction Groups. These results do not support the anhedonic hypothesis that dopamine containing neurons mediate reward processes and were interpreted within a sensory-motor conditioning framework.

Animals↗
PubMed1982

Avoidance performance, cue and response-choice discrimination after neuroleptic treatment.

The effects of pimozide on discriminated avoidance performance in a Y-maze were evaluated in mice. Relatively low doses of pimozide (0.4 mg/kg) retarded acquisition of an active avoidance response. The avoidance deficit induced by this dosage was largely eliminated among mice that had received either 1 or 2 previous avoidance training sessions, but was still evident in mice treated with a higher drug dosage (0.8 mg/kg). If mice were initially trained in the drug condition, the disruptive effects were still evident in a later test conducted in the absence of the drug treatment. In contrast to the avoidance deficits, pimozide did not disrupt the acquisition or the performance of a cue- or response-choice discrimination. That is, once a running response was initiated (on avoidance trials) pimozide treated animals appeared capable of appropriately directing the response. It is suggested that at the dosages used pimozide did not affect S-S learning or learning response-outcome contingencies, but rather hindered performance owing to deficits in response initiation processes. Moreover, within a task involving aversive motivation pimozide did not appear to reduce the reinforcement derived for correct responding.

Animals↗
PubMed1982

Establishment of secondary reinforcement in sign tracking and place preference tests following pimozide treatment.

The effects of pimozide (1.0 mg/kg), a DA receptor blocker, on the capacity of environmental stimuli to acquire secondary reinforcing properties was investigated using two different paradigms. In the first experiment rats pretreated with either pimozide or its vehicle, were exposed to light-food pairings. When tested under drug-free extinction conditions, these animals approached the light cue significantly more frequently than did control animals who never had the cue associated with food during training. No differences in approach behavior were observed between the pimozide and vehicle groups that received the light-food pairings. The second experiment employed a place preference paradigm where animals were confined in distinctive compartments under reinforced (S+) or nonreinforced (S-) conditions. Pimozide and vehicle treated animals, when tested drug-free and given unrestricted access to both chambers under extinction conditions, spent comparable amounts of time in the S+ chamber relative to vehicle subjects that had never received food in either chamber. The results from these two studies indicate that an animal's ability to code relevant environmental information and to use this encoded information to guide and direct food seeking behavior is relatively independent of dopaminergic activity. The results also have significance for any theory which assumes that dopamine mediates reward processes.

Animals↗
PubMed1981

Effects of pimozide on nordiscriminated and discriminated performance in the pigeon.

The effects of pimozide (0.06, 0.18, 0.30 mg/kg), a dopamine receptor blocker, on nondiscriminated and discriminated performance were assessed in pigeons using a Latin Square design. In Experiment 1 a dose-dependent decrease in responding was observed with a variable interval 3-min schedule of reinforcement. More detailed analyses showed that total response rate, running response rate, and post-reinforcement pause all showed the same dose-dependent relationship. In Experiment 2 a successive discrimination task was employed to determine if pimozide affects a previously learned association between environmental stimuli. Each pigeon was first trained on the discrimination and then injected with the same doses as in Experiment 1. Although pimozide reduced responding in a dose-related fashion, a corresponding decrease in accuracy of responding was not evident. It was concluded that pimozide has a general response debilitating effect and that dopaminergic neurons probably are not involved in subserving associative processes.

Animals↗
PubMed1981

Use of a fixed consecutive number schedule of reinforcement to investigate the effects of pimozide on behavior controlled by internal and external stimuli.

The effects of the neuroleptic pimozide, a specific dopamine receptor blocker, on behavior maintained under different degrees of stimulus control was examined by using a fixed consecutive number (FCN) schedule of reinforcement with pigeons. This schedule requires that at least eight consecutive responses be made on one key (work key) before a response on a second key (reinforcement key) will be reinforced. For half the birds no change in external stimuli accompanied the eight response (FCN-8) while for the other half the color of the work key changed from white to red after the eight peck (FCN-SD). Both schedules resulted in equal rates of baseline responding. Four doses of pimozide (vehicle, 0.1, 0.3, 0.5 mg/kg) were administered in a Latin Square sequence after baseline responding was stable. Similar pimozide-induced decreases in responding were observed in both conditions. However, pimozide selectively altered response patterns under the FCN-8 condition. The failure of the FCN-SD procedure to display a similar effect demonstrated that the use of salient exteroceptive stimuli can modulate behavioral deficits induced by pimozide. This conclusion has important implications for theories hypothesizing that dopamine subserves reward processes.

Animals↗