diff --git a/demo/illusions/circular.ipynb b/demo/illusions/circular.ipynb
index f856bf60..99864854 100644
--- a/demo/illusions/circular.ipynb
+++ b/demo/illusions/circular.ipynb
@@ -297,6 +297,13 @@
     "display(ui, out)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Specification of `frequency`, `ring_width`, or `n_rings`:"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -342,35 +349,9 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from stimuli.illusions.circular import circular_white"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "## Parameterization"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "params = {\n",
-    "    \"visual_size\": (10., 10.),\n",
-    "    \"ppd\": 40.0,\n",
-    "    \"frequency\": 1.,\n",
-    "    \"intensity_discs\": (0., 1.),\n",
-    "    \"intensity_background\": 0.5,\n",
-    "    \"intensity_target\": 0.5,\n",
-    "    \"target_indices\": 3,\n",
-    "}\n",
+    "from stimuli.illusions.circular import circular_white\n",
     "\n",
-    "stim = circular_white(**params)\n",
-    "plot_stim(stim)\n",
-    "plt.show()"
+    "help(circular_white)"
    ]
   },
   {
@@ -391,7 +372,7 @@
     "    \"visual_size\": (10., 10.),\n",
     "    \"ppd\": 40.0,\n",
     "    \"frequency\": 1.5,\n",
-    "    \"intensity_discs\": (0., 1.),\n",
+    "    \"intensity_rings\": (0., 1.),\n",
     "    \"intensity_background\": 0.5,\n",
     "    \"intensity_target\": 0.5\n",
     "}\n",
@@ -403,13 +384,6 @@
     "plt.show()"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "## Interactive"
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -417,51 +391,52 @@
    "outputs": [],
    "source": [
     "# Define widgets\n",
-    "w_length = iw.IntSlider(value=10, min=10, max=30, description=\"height [deg]\")\n",
-    "w_width = iw.IntSlider(value=10, min=10, max=30, description=\"width [deg]\")\n",
+    "w_length = iw.IntSlider(value=5, min=1, max=10, description=\"heigh/width [deg]\")\n",
     "w_ppd = iw.IntSlider(value=40, min=1, max=64, description=\"ppd\")\n",
-    "w_size = iw.HBox([w_length, w_width, w_ppd])\n",
-    "w_radius = iw.FloatSlider(value=1., min=0.1, max=2.0, description=\"Frequency\")\n",
-    "w_idisc1 = iw.FloatSlider(value=0.0, min=0., max=1.0, description=\"intensity disc 1\")\n",
-    "w_idisc2 = iw.FloatSlider(value=1.0, min=0., max=1.0, description=\"intensity disc 2\")\n",
-    "w_iback = iw.FloatSlider(value=0.5, min=0., max=1.0, description=\"intensity background\")\n",
-    "w_itarget = iw.FloatSlider(value=0.5, min=0., max=1.0, description=\"intensity target\")\n",
-    "w_intensities = iw.HBox([w_idisc1, w_idisc2, w_iback, w_itarget])\n",
     "\n",
-    "ui = iw.VBox([w_size, w_radius, w_intensities])\n",
+    "w_frequency = iw.FloatSlider(value=1, min=0.1, max=3.0, description=\"frequency\")\n",
+    "w_target_idx = iw.IntSlider(value=1, min=0, max=8, description=\"idx target\")\n",
+    "\n",
+    "w_iback = iw.FloatSlider(value=0.5, min=0.0, max=1.0, description=\"background intensity\")\n",
+    "w_itarget = iw.FloatSlider(value=0.5, min=0.0, max=1.0, description=\"target intensity\")\n",
+    "w_irings = iw.FloatRangeSlider(value=[0.0, 1.0], min=0.0, max=1.0, step=0.1, description=\"intensities\")\n",
+    "\n",
+    "# Layout\n",
+    "b_size = iw.HBox([w_length, w_ppd])\n",
+    "b_intensities = iw.HBox([w_itarget, w_iback, w_irings])\n",
+    "b_rings = iw.HBox([w_frequency, w_target_idx])\n",
+    "ui = iw.VBox([b_size, b_rings, b_intensities])\n",
     "\n",
     "def show_circular(\n",
-    "    height=None,\n",
-    "    width=None,\n",
+    "    length=None,\n",
     "    ppd=None,\n",
     "    frequency=None,\n",
-    "    intensity_disc1=None,\n",
-    "    intensity_disc2=None,\n",
+    "    target_indices=None,\n",
+    "    intensity_rings=None,\n",
     "    intensity_background=None,\n",
-    "    intensity_target=None,    \n",
+    "    intensity_target=None,\n",
     "):\n",
     "\n",
     "    stim = circular_white(\n",
-    "        visual_size=(height, width),\n",
+    "        visual_size=(length, length),\n",
     "        ppd=ppd,\n",
     "        frequency=frequency,\n",
     "        intensity_background=intensity_background,\n",
-    "        intensity_discs=(intensity_disc1, intensity_disc2),\n",
+    "        intensity_rings=intensity_rings,\n",
     "        intensity_target=intensity_target,\n",
-    "        target_indices=(1)\n",
+    "        target_indices=target_indices\n",
     "    )\n",
     "    plot_stim(stim)\n",
     "\n",
     "\n",
     "out = iw.interactive_output(show_circular,\n",
     "                            {\n",
-    "                                \"height\": w_length,\n",
-    "                                \"width\": w_width,\n",
+    "                                \"length\": w_length,\n",
     "                                \"ppd\": w_ppd,\n",
-    "                                \"frequency\": w_radius,\n",
+    "                                \"frequency\": w_frequency,\n",
+    "                                \"target_indices\": w_target_idx,\n",
     "                                \"intensity_background\": w_iback,\n",
-    "                                \"intensity_disc1\": w_idisc1,\n",
-    "                                \"intensity_disc2\": w_idisc2,\n",
+    "                                \"intensity_rings\": w_irings,\n",
     "                                \"intensity_target\": w_itarget,\n",
     "                            })\n",
     "\n",
@@ -483,34 +458,57 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from stimuli.illusions.circular import circular_bullseye"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "## Parameterization"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "params = {\n",
-    "    \"visual_size\": (10., 10.),\n",
-    "    \"ppd\": 40.0,\n",
-    "    \"frequency\": 1.,\n",
-    "    \"intensity_discs\": (0., 1.),\n",
-    "    \"intensity_background\": 0.5,\n",
-    "    \"intensity_target\": 0.5,\n",
-    "}\n",
+    "from stimuli.illusions.circular import circular_bullseye\n",
     "\n",
-    "stim = circular_bullseye(**params)\n",
-    "plot_stim(stim)\n",
-    "plt.show()"
+    "help(circular_bullseye)\n",
+    "\n",
+    "# Define widgets\n",
+    "w_length = iw.IntSlider(value=5, min=1, max=10, description=\"heigh/width [deg]\")\n",
+    "w_ppd = iw.IntSlider(value=40, min=1, max=64, description=\"ppd\")\n",
+    "\n",
+    "w_frequency = iw.FloatSlider(value=1, min=0.1, max=3.0, description=\"frequency\")\n",
+    "\n",
+    "w_iback = iw.FloatSlider(value=0.5, min=0.0, max=1.0, description=\"background intensity\")\n",
+    "w_itarget = iw.FloatSlider(value=0.5, min=0.0, max=1.0, description=\"target intensity\")\n",
+    "w_irings = iw.FloatRangeSlider(value=[0.0, 1.0], min=0.0, max=1.0, step=0.1, description=\"intensities\")\n",
+    "\n",
+    "# Layout\n",
+    "b_size = iw.HBox([w_length, w_ppd])\n",
+    "b_intensities = iw.HBox([w_itarget, w_iback, w_irings])\n",
+    "b_rings = iw.HBox([w_frequency, w_nrings])\n",
+    "ui = iw.VBox([b_size, w_frequency, b_intensities])\n",
+    "\n",
+    "def show_bullseye(\n",
+    "    length=None,\n",
+    "    ppd=None,\n",
+    "    frequency=None,\n",
+    "    intensity_rings=None,\n",
+    "    intensity_background=None,\n",
+    "    intensity_target=None,\n",
+    "):\n",
+    "\n",
+    "    stim = circular_bullseye(\n",
+    "        visual_size=(length, length),\n",
+    "        ppd=ppd,\n",
+    "        frequency=frequency,\n",
+    "        intensity_background=intensity_background,\n",
+    "        intensity_rings=intensity_rings,\n",
+    "        intensity_target=intensity_target,\n",
+    "    )\n",
+    "    plot_stim(stim)\n",
+    "\n",
+    "\n",
+    "out = iw.interactive_output(show_bullseye,\n",
+    "                            {\n",
+    "                                \"length\": w_length,\n",
+    "                                \"ppd\": w_ppd,\n",
+    "                                \"frequency\": w_frequency,\n",
+    "                                \"intensity_background\": w_iback,\n",
+    "                                \"intensity_rings\": w_irings,\n",
+    "                                \"intensity_target\": w_itarget,\n",
+    "                            })\n",
+    "\n",
+    "display(ui, out)"
    ]
   },
   {