Electrodermal activity is characterized by the superposition of what appear to be single distinct skin conductance responses (SCRs). Classic trough-to-peak analysis of these responses is impeded by their apparent superposition. A deconvolution approach is proposed, which separates SC data into continuous signals of tonic and phasic activity. The resulting phasic activity shows a zero baseline, and overlapping SCRs are represented by predominantly distinct, compact impulses showing an average duration of less than 2 s. A time integration of the continuous measure of phasic activity is proposed as a straightforward indicator of event-related sympathetic activity. The quality and benefit of the proposed measure is demonstrated in an experiment with short interstimulus intervals as well as by means of a simulation study. The advances compared to previous decomposition methods are discussed.

This paper proposes a method for adaptive testing that is less complicated than the commonly used transformed up-down methods (I up 2 down, 1 up 3 down, etc.). In addition, the weighted up-down method can converge to any desired point ofthe psychometric function. The rule is very simple: Each correct response leads to a decrease in signal level, each incorrect response to an increase. The only difference from the simple up-down method (l up 1 down) is that the steps upward and the steps downward are of a different size. The straightforward construction of the novel procedure pays off in efficiency and stability: A Monte Carlo simulation reveals a definite advantage, though small, of the weighted up-down method over the l-up-2-down rule.The simple up-down method (I up I down) converges to the X 50 point of the psychometric function. This is not appropriate for tasks in which the chance performance is high. For two-interval forced-choice (2IFC) tasks (chance performance: 50%), X 7 5 would be the halfway point. This point would be the most natural choice for a threshold estimate.

Skin conductance (SC) data are usually characterized by a sequence of overlapping phasic skin conductance responses (SCRs) overlying a tonic component. The variability of SCR shapes hereby complicates the proper decomposition of SC data. A method is proposed for full decomposition of SC data into tonic and phasic components. A two-compartment diffusion model was found to adequately describe a standard SCR shape based on the process of sweat diffusion. Nonnegative deconvolution is used to decompose SC data into discrete compact responses and at the same time assess deviations from the standard SCR shape, which could be ascribed to the additional process of pore opening. Based on the result of single non-overlapped SCRs, response parameters can be estimated precisely as shown in a paradigm with varying inter-stimulus intervals.

Research highlights► Film audio tracks are more powerful than music in eliciting piloerection. ► Objective measurement of piloerection avoids typical biases of self-report measures. ► Piloerection is primarily accompanied by an increase of phasic EDA and respiration depth. ► The separation call hypothesis is favored over the peak arousal hypothesis. ► Emotional piloerection indicates the state of being moved or touched.

A new unbiased adaptive procedure is described that requires only half as many presentations in achieving the same precision as the well-known two-interval forced-choice (2IFC) 2-step procedure. The procedure is based on a yes-no task which avoids redundant presentation time. Furthermore, certain psychophysical studies can only be realized with yes-no tasks. Every trial contains randomly presented signals or noises and the answer is either yes or no. The outcome (hit, miss, false alarm, correct rejection) is taken into account by adjusting the signal level in a staircase manner. The adjustment matrix is set up to induce a neutral response criterion. Its convergence point can be adjusted at will. The single-interval adjustment-matrix (SIAM) procedure is compared to von Békésy and 2IFC transformed up-down methods using a Monte-Carlo simulation. The SIAM procedure proves to be the fastest of the unbiased procedures. A test on four subjects verified these results. Implications for optimum track length and the number of reversals to discard are discussed.

This paper evaluates an adaptive staircase procedure for threshold estimation that is suitable for unforced-choice tasks-ones with the additional response alternative don't know. Within the framework of a theory of indecision, evidence is developed that fluctuations of the response criterion are much less detrimental to unforced-choice tasks than to yes/no tasks. An adaptive staircase procedure for unforced-choice tasks is presented. Computer simulations show a slight gain in efficiency if don't know responses are allowed, even if response criteria vary. A behavioral comparison with forcedchoice and yes/no procedures shows that the new procedure outdoes the other two with respect to reliability. This is especially true for naive participants. For well-trained participants it is also slightly more efficient than the forced-choice procedure, and it produces a smaller systematic error than the yes/no procedure. Moreover, informal observations suggest that participants are more comfortable with unforced tasks than with forced ones.

The memory of auditory random waveforms (i.e., noise) is a special case of auditory memory for sensory information. Five experiments are reported that evaluate the dynamics of this storage system as well as interactions with new input. Periodic waveforms can be discriminated from uncorrelated noise by naive listeners up to a cycle length of 20 s, with the major decline in performance between 5 and 10 s. Even single repetitions of a piece of the waveform can be detected up to a stimulus onset asynchrony (SOA) of 6 s. The capacity of this storage system is limited to a few items of, in total, a few hundred milliseconds length. Within this capacity, however, items do not interfere strongly. These results are compatible with the view that auditory sensory memory is a modality-specific module of short-term memory.

Increasing attention is drawn to the investigation of piloerection (or goose bumps) in response to strong emotional experiences. This research is complicated by the need to rely on self-report measures. This article proposes an efficient method for the objective and continuous measurement of piloerection. It is based on an optical recording device combined with a discrete Fourier transform analysis quantifying the frequency power related to visible piloerection. The validity of the method was demonstrated in a proof-of-principle experiment involving a person with the exceptional ability to control the erection of his hair. The method reliably mapped all occurrences of visible piloerection and provided insight into the temporal dynamics of the underlying physiological process. It thus proved suitable for future experimental investigation of human piloerection.