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H Lachnit

Publications and source records attributed to H Lachnit.

At least 19 recordsLinked to original sources
PubMed1996

[Are there differences in processing times of variously complex rules in differential eyelid conditioning?].

Two logical relations, conjunction (AND) and exclusive disjunction (XOR) differ in formal complexity as well as in observable difficulties. AND results in less errors, fewer trials to criterion, and shorter processing time per trial than XOR. Two paradigms of differential classical conditioning are based on these rules. Negative patterning (A+, B+, AB-) equals XOR, and positive patterning (A-, B-, AB+) equals AND. We studied experimentally whether or not differences in processing time per trial are reflected in different optimal interstimulus intervals in human eyelid conditioning. Results of four groups (AND/XOR x 400/1200 ms; each group n = 10) suggest that differential conditioning could be observed in positive patterning (800-1000 ms) earlier than in negative patterning (1000-1200 ms).

Adult↗
PubMed1994

[Inductive versus associative processes in stimulus discrimination].

The experiment reported here was an attempt to demonstrate that the solution of specific discrimination problems is based on rules rather than on differences in associative strengths. With positive and negative patterning as examples, we examined whether or not the solution of the discrimination problem depends on the number of reinforcements for each individual stimulus when the total number of reinforcements is kept constant. This was achieved by manipulating the number of stimuli used. We also examined the transfer to new stimuli. Forty subjects took part in a 2 x 2-factorial experiment with anticipatory skin conductance responses as the dependent variable. All the results were in accordance with the assumption of rule based problem solution. The amount of discrimination was independent of the number of reinforcements for each stimulus. Furthermore, according to results of concept formation studies, an asymmetry in transferring the solution to new stimuli was observed.

Adult↗
PubMed1994

[Is there a feature-positive effect in classical conditioning in humans?].

Jenkins and Sainsbury (1969, 1979) first described an asymmetry in pigeon's operant discrimination learning which they called a feature-positive effect. Subsequent studies demonstrated that other animals as well as humans also show a similar asymmetry. The effect is often explained as being caused by a bias in information processing which results from the neglect of negative information as a discriminative cue. The effect has also been observed in classical conditioning experiments, but not yet with human subjects. Sometimes, however, a reversal of the asymmetry, i.e., a feature-negative effect, has been observed. The experiment reported here primarily intended to demonstrate a feature-positive effect in a classical conditioning procedure with human subjects. Secondly, we also wanted to test an alternative explanation of the feature-positive effect. We found that a substantial feature-positive effect does indeed occur during classical conditioning in human subjects. Our results, however, did not fully support the alternative explanation based on rule learning.

Adult↗
PubMed1994

[Skin conduction as an indicator of cognitive and emotional processes].

Classical conditioning experiments can be used to study both cognition and emotions. In studies involving human subjects two different scores based on the human skin conductance response are generally used: the "first interval responses" (FIR) and the "second interval responses" (SIR). The SIR is thought to reflect cognitive but not emotional processes, while the FIR is assumed to reflect both. An experiment with two groups of subjects (n = 20 each) was run in order to demonstrate that the SIR indeed is able to reflect emotional processes. Each group was trained with five different conditioned stimuli, each of which was paired with a specific unconditioned stimulus. These unconditioned stimuli varied in aversiveness. Immediately after training, skin conductance responses to combinations of already trained conditioned stimuli were examined. The sequence of testing was varied across groups. Our results clearly showed that the SIR reflected aversiveness, while the FIR was confounded by orienting responses under these experimental conditions.

Adult↗
PubMed1992

Mobilization of cognitive resources and the generation effect.

The generation effect refers to the memory advantage of words that have been generated rather than read. Such a read-generate comparison confounds qualitative task differences and raises methodological problems. A revised methodology is proposed circumventing these problems in that the encoding task is held constant and all stimuli have to be generated, but the degree of generativeness (i.e. the amount of cueing) is varied. In Experiment 1, 1, the (refined version of the) generation effect is demonstrated in a within-subjects design; with increasing generation activity left to the subject, free recall performance increases. No effect is obtained for degree of target masking. The same finding is replicated and shown to be independent of self-paced study time when generative activity is manipulated between subjects (Experiment 2) or within subjects (Experiment 3). As all learning trials involve generation, encoding time is controlled statistically, and free recall is used as a measure of memory, this refined generation effect cannot be explained as an artifact of selective attention or elaboration. Rather, generative activity seems to increase the mobilization of cognitive resources. This motivational account is supported by Experiment 4 showing an enhanced generation effect for positive mood.

Adult↗
PubMed1990

Speed and accuracy effects of fingers and dexterity in 5-choice reaction tasks.

In two experiments we studied the influence of dexterity (controls, typists, pianists) and of differences between the five fingers of the dominant hand on speed and accuracy in a 5-choice reaction task. We used five coloured squares (Blue, Green, Yellow, Red, White) as stimuli, randomly varying foreperiods (3-10s) and an intermediate stimulus-response-compatibility. The results reported here were independent of sex, foreperiods, and colour of stimuli. In Experiment 1 (N = 168) with three groups (controls, typists, pianists) thumb and little finger showed significantly shorter reaction times than did index, middle, and ring finger. This difference did not interact with dexterity. Averaged across all the fingers typists and controls did not differ. Pianists showed significantly shorter reaction times than these two groups. Experiment 2 (N = 40) replicated all these findings. In both experiments groups did not differ in speed-accuracy-trade-off. The accuracy of the fingers was independent of dexterity. In all three groups the little finger showed the lowest rate of false alarms and the highest degree of reliability. The frequency distribution of finger confusions in all groups was in accordance with the spatial proximity of fingers: the closer their proximity the higher were the rates of confusion. In addition, these distributions showed an asymmetry across all three groups. The finger next to the 'correct' finger in direction towards the thumb showed the highest false alarm rate in each case.

Adolescent↗
PubMed1988

The Rescorla-Wagner theory does not predict contextual control of phasic responses in transswitching.

Theoretical predictions regarding differential phasic responding to the same phasic conditioned stimulus in two different tonic contexts, generated by a computer simulation of the Rescorla-Wagner theory of classical conditioning, were compared to empirical evidence of phasic switching in two studies of transswitching of the skin conductance response in humans. Significant phasic switching was found in both studies, but the Rescorla-Wagner theory substantially underestimated the obtained differences. It was shown that the theory predicts phasic differences that are more in accord with empirical data when the salience (alpha) of the contextual stimuli is assumed to be much greater than the salience (alpha) of the phasic conditioned stimulus. This modification in salience relationships, however, makes the Rescorla-Wagner theory more like Asratyan's theory of transswitching. Analysis of both tonic and phasic differentiation in experimental groups run with two different phasic stimuli AND two different tonic stimuli or with two phasic stimuli and only one tonic stimulus provided support for the conclusion that tonic response differentiation is a necessary precondition for obtaining phasic switching. It is suggested that the Rescorla-Wagner theory fails to account for phasic switching because it treats tonic and phasic stimuli as essentially equivalent, ignoring the fact that the tonic stimulus is present prior to the time that phasic stimuli occur and that responses to the tonic stimuli can occur during the period following tonic stimulus onset and preceding the administration of phasic stimuli.

Arousal↗
PubMedDate not supplied

Acquisition of a unique cue in positive and negative patterning?

Forty college students received a classical differential conditioning procedure involving both positive and negative patterning, each of these being associated with a different pair of stimuli. In positive patterning, elemental stimuli, A and B, were presented without an unconditioned stimulus while their compound, AB, was paired with electric shock. In negative patterning, elemental stimuli, C and D, were paired with shock while their compound, CD, remained unpaired. Thirty of these subjects then received a negative patterning transfer test on new stimuli, while ten subjects received a positive patterning transfer test. First interval response (FIR) and second interval response (SIR) were measured. During initial acquisition, positive patterning occurred in both dependent measures, but negative patterning was present only in the SIR. The transfer tests showed almost significant transfer of positive patterning in FIR and SIR. Negative patterning showed significant transfer neither in FIR nor SIR. It was concluded that, although elementary models of conditioning can explain positive patterning on the basis of summation of excitation from the elements to the compound, the occurrence of negative patterning in the SIR and the almost significant transfer of positive patterning in FIR and SIR appear to require the additional assumption of a unique cue.

Adult↗
PubMedDate not supplied

Simultaneous classical conditioning of two effector systems.

The experiment reported here was an attempt to develop an experimental procedure for independent classical conditioning of two different response systems, the skin conductance response (SCR) and the eyelid response. In a differential conditioning design with human subjects (N = 50) two different unconditioned stimuli were used, a white noise (US1) and airpuff (US2). Two conditioned stimuli (CS11 and CS12) were paired with US1, and two other CSs (CS21 and CS22) were paired with US2. A special trial architecture was used to accomplish measurement of both anticipatory SCR and eyelid responses during each trial. Significant eyelid differentiation as well as significant SCR (especially second interval responses) differentiation developed.

Adult↗
PubMedDate not supplied

Component summation or configuration in human eyelid conditioning depends upon stimulus properties.

The experiment reviewed here merges Garner's (1974) distinction of separable and integral stimulus properties with the field of Pavlovian eyelid conditioning with human subjects. According to one rule, two sets of stimuli (separable vs integral) were constructed. A differential compound conditioning procedure was used with one group of subjects being trained with a subset of the separable material and then tested with a new subset. The same procedure was used with a second group but with integral material. The experiment showed a reversal of conditioning effects, depending on the properties of stimuli. Separable compounds showed results as predicted by elementistic conditioning theories: the associative values of the elements summed up. With integral compounds, the associative values of the elements were irrelevant. Instead, integral compounds were processed and classified primarily on the basis of similarity.

Arousal↗
PubMedDate not supplied

Pavlovian conditioning and rule learning.

The experiment reviewed here was an attempt to show that two differential Pavlovian conditioning designs, namely positive and negative patterning, can best be understood as rule learning. First, it is shown that positive patterning is equivalent to the logical rule of conjunction (AND) and that negative patterning is equivalent to the logical rule of exclusive disjunction (XOR). It is assumed that in order to learn both kinds of discrimination subjects learn to use the according rule. If this is the case, the observed differentiation should be independent of the number of reinforcements for each individual stimulus. Second, subjects should be able to transfer the rule to new stimuli. Forty human subjects were randomly divided into four groups (N = 10 each). Two factors were manipulated independently between subjects: (1) positive vs negative patterning, and (2) 2 vs 4 pairs of trained stimuli. Second interval skin conductance responses were measured. During initial acquisition positive as well as negative patterning occurred independently of number of pairs of trained stimuli (with total amount of training kept constant). Furthermore, AND as well as XOR could be transferred to new stimuli.

Adult↗
PubMedDate not supplied

Are anticipatory first and second interval skin conductance responses indicators of predicted aversiveness?

The experiment reviewed here was an attempt to examine whether or not magnitudes of first and second interval skin conductance responses (FIR, SIR) to different conditioned stimuli (CS), each predicting another unconditioned stimulus (US), mirror the aversiveness of the predicted USs. Twenty human subjects received a differential Pavlovian conditioning training with five CSs, each one paired eight times with a specific US. Magnitudes of FIR and SIR elicited by CSs increased with increasing aversiveness of the USs predicted. It is concluded therefore that the SIR is not a mere indicator of a cognitive expectancy process but is also affected by emotional aspects.

Adult↗
PubMedDate not supplied

Pavlovian conditional stimuli cannot always be defined solely in physical terms.

Twenty-four university students received differential Pavlovian conditioning with two colored stimuli separately accompanied by shock, and two other colored stimuli separately presented without shock. The reinforced and nonreinforced pairs of stimuli both contained complementary elements. After differentiation between the reinforced and nonreinforced elements was established, the complementary pairs were each additively mixed, (i.e., presented at the same time and in the same locus), producing two identical white compounds (established by pilot study). The subjects' skin-conductance responses to the two compounds showed that their different conditioning histories did not result in different responses. Rather, a simple declining function was obtained, resembling habituation or extinction. It was concluded that the definition of the conditional stimulus as a physical event is inappropriate in studies in which physically different stimuli may result in identical internal processes (or phenomenologic experiences)--for example, in additive color mixture.

Adult↗
PubMedDate not supplied

Pavlovian conditioning with proximal stimuli.

This experiment was conducted with the objective of demonstrating that the effective stimuli in Pavlovian Conditioning are not environmental stimuli but internal physiological processes elicited by environmental input (proximal stimuli). In order to achieve the objective, afterimages in color vision were used: looking at a diffuse lightened circle after seeing a red circle yields an image of a green circle. A differential conditioning paradigm with two sequential compounds was run. In one group (G+B-: n1 = 10), a red circle followed by a green circle was paired with shock, whereas a red circle followed by a blue circle remained unpaired. A second group (G-B+: n2 = 10) received red-blue paired trials and unpaired red-green trials. Immediately after that training, subjects were tested with a new, never trained sequential compound: a red circle followed by a diffuse lightened circle. Furthermore, they were tested with the already trained compounds. Taking the environmental point of view, the never trained stimulus should elicit an orienting response lying in between the excitatory reaction to the paired stimulus and the inhibitory reaction to the unpaired stimulus. From the proximal point of view, the diffuse light should elicit an excitatory reaction in group G+B- and an inhibitory reaction in group G-B+. Electrodermal conditioned anticipatory and omission responses were measured. The results supported the proximal hypothesis. Hence, defining input in environmental terms may be the wrong way. Instead, in conceptualizing the stimulus in conditioning, the following should be considered: the processing organism itself is creating the effective stimuli.

Adult↗
PubMedDate not supplied

Extending the Rescorla-Wagner theory to account for transswitching.

This article is a brief response to commentaries made by Bond and Siddle (1988) and Lovibond (1988) to our article (Kimmel & Lachnit, 1988) outlining some of the difficulties encountered by the Rescorla-Wagner theory in predicting the outcome of transswitching experiments. We show that Bond and Siddle's assertion that increasing the value of beta would "bring the model into line with the empirical data" (p. 186) is incorrect. Increasing beta in simulated transswitching experiments causes the theory to predict a more rapid increase in associative values, to higher levels, but does not change the degree of predicted phasic switching. We agree with Lovibond's observation that the Rescorla-Wagner theory can predict phasic switching more effectively if it is assumed that an unobserved additional stimulus is present whenever the phasic stimulus occurs in positive tonic segments and a different unobserved additional stimulus is present whenever the phasic stimulus occurs in negative tonic segments. But this kind of usage of the "unique cue hypothesis" does little more then immunize a theory against problematic empirical findings. When the salience of the unique cue is increased relative to that of the stimuli that are actually physically present, simulated transswitching experiments show greater and greater phasic switching. But, unless there is a good a priori reason to postulate such unique cues, or unless the unique cue hypothesis leads to empirically testable new hypotheses, it does not provide a scientifically useful solution to the theory's problem with transswitching.

Association Learning↗